Technical note: Radiological clinical equivalence for phantom materials in carbon ion therapy

PURPOSE

As carbon ion radiotherapy increases in use, there are limited phantom materials for heterogeneous or anthropomorphic phantom measurements. This work characterized the radiological clinical equivalence of several phantom materials in a therapeutic carbon ion beam.

METHODS

Eight materials were tested for radiological material-equivalence in a carbon ion beam. The materials were computed tomography (CT)-scanned to obtain Hounsfield unit (HU) values, then irradiated in a monoenergetic carbon ion beam to determine relative linear stopping power (RLSP). The corresponding HU and RLSP for each phantom material were compared to clinical carbon ion calibration curves. For absorbed dose comparison, ion chamber measurements were made in the center of a carbon ion spread-out Bragg peak (SOBP) in water and in the phantom material, evaluating whether the material perturbed the absorbed dose measurement beyond what was predicted by the HU-RLSP relationship.

RESULTS

Polyethylene, solid water (Gammex and Sun Nuclear), Blue Water (Standard Imaging), and Techtron HPV had measured RLSP values that agreed within ±4.2% of RLSP values predicted by the clinical calibration curve. Measured RLSP for acrylic was 7.2% different from predicted. The agreement for balsa wood and cork varied between samples. Ion chamber measurements in the phantom materials were within 0.1% of ion chamber measurements in water for most materials (solid water, Blue Water, polyethylene, and acrylic), and within 1.9% for the rest of the materials (balsa wood, cork, and Techtron HPV).

CONCLUSIONS

Several phantom materials (Blue Water, polyethylene, solid water [Gammex and Sun Nuclear], and Techtron HPV) are suitable for heterogeneous phantom measurements for carbon ion therapy. Low density materials should be carefully characterized due to inconsistencies between samples.

Prediabetes and Associated Risk of Cardiovascular Events and Chronic Kidney Disease Among Adult Survivors of Childhood Cancer in the St Jude Lifetime Cohort

PURPOSE

Little is known about the prevalence of prediabetes and associated risk of cardiovascular events and chronic kidney disease (CKD) with this reversable condition in survivors.

METHODS

Prevalence of prediabetes (fasting plasma glucose 100-125 mg/dL or hemoglobin A1c 5.7%-6.4%) and diabetes was clinically assessed in 3,529 adults ≥5 years from childhood cancer diagnosis and 448 controls stratified by age. Cox proportional hazards regression estimated progression from prediabetes to diabetes, and risk of future cardiac events, stroke, CKD, and death.

RESULTS

Among survivors, median age 30 years (IQR, 18-65), and the prevalence of prediabetes was 29.2% (95% CI, 27.7 to 30.7) versus 18.1% (14.5 to 21.6) in controls and of diabetes was 6.5% (5.7 to 7.3) versus 4.7% (2.7 to 6.6). By age 40-49 years, more than half of the survivors had prediabetes (45.5%) or diabetes (14.0%). Among 695 survivors with prediabetes and longitudinal follow-up, 68 (10%; median follow-up, 5.1 years) progressed to diabetes. After adjustment for demographic factors and body composition, risk of progression was associated with radiation exposure to the pancreatic tail ≥10 Gy (hazard ratio [HR], 2.7 [95% CI, 1.1 to 6.8]) and total-body irradiation (4.4 [1.5 to 13.1]). Compared with survivors with normal glucose control, adjusting for relevant treatment exposures, those with prediabetes were at increased risk of future myocardial infarction (HR, 2.4 [95% CI, 1.2 to 4.8]) and CKD (2.9 [1.04 to 8.15]), while those with diabetes were also at increased risk of future cardiomyopathy (3.8 [1.4 to 10.5]) or stroke (3.4 [1.3 to 8.9]).

CONCLUSION

Prediabetes is highly prevalent in adult survivors of childhood cancer and independently associated with an increased risk of future cardiovascular and kidney complications. Prediabetes, a modifiable risk factor among childhood cancer survivors, represents a new target for intervention that may prevent subsequent morbidity and mortality.

Impact of Risk-Based therapy on late morbidity and mortality in neuroblastoma survivors: a report from the childhood cancer survivor study

BACKGROUND

Early efforts at risk-adapted therapy for neuroblastoma are predicted to result in differential late effects; the magnitude of these differences have not been well-described.

METHODS

Late mortality, subsequent malignant neoplasms (SMN), and severe/life-threatening chronic health conditions (CHCs), graded according to CTCAE v4.03, were assessed among 5-year CCSS survivors of neuroblastoma diagnosed 1987-1999. Using age, stage at diagnosis, and treatment, survivors were classified into risk groups (low [n = 425]; intermediate [n = 252]; high [n = 245]). Standardized mortality ratios (SMR) and standardized incidence ratios (SIR) of SMNs were compared to matched population controls. Cox regression models estimated hazard ratios (HR) and 95% confidence intervals (CI) for CHC compared to 1,029 CCSS siblings.

RESULTS

Among survivors (49.8% male; median age 21 years, range 7-42; median follow-up 19.3 years, range 5-29.9), 80% with low-risk disease were treated with surgery alone, while 79.1% with high-risk disease received surgery, radiation, chemotherapy ± autologous stem cell transplant (ASCT). All-cause mortality was elevated across risk groups (SMRhigh=27.7 [21.4-35.8]; SMRintermediate=3.3 [1.7-6.5]; SMRlow=2.8 [1.7-4.8]). SMN risk was increased among high- and intermediate-risk survivors (SIRhigh=28.0 [18.5-42.3]; SIRintermediate=3.7 [1.2-11.3]), but did not differ from the US population for survivors of low-risk disease. Compared to siblings, survivors had an increased risk of grade 3-5 CHCs, particularly among those with high-risk disease (HRhigh=16.1 [11.2-23.2]; HRintermediate=6.3 [3.8-10.5]; HRlow=1.8 [1.1-3.1]).

CONCLUSION

Survivors of high-risk disease treated in the early days of risk stratification carry a markedly elevated burden of late recurrence, SMN, and organ-related multi-morbidity, while survivors of low/intermediate-risk disease have a modest risk of late adverse outcomes.

Polygenic risk scores, radiation treatment exposures and subsequent cancer risk in childhood cancer survivors

Survivors of childhood cancer are at increased risk for subsequent cancers attributable to the late effects of radiotherapy and other treatment exposures; thus, further understanding of the impact of genetic predisposition on risk is needed. Combining genotype data for 11,220 5-year survivors from the Childhood Cancer Survivor Study and the St Jude Lifetime Cohort, we found that cancer-specific polygenic risk scores (PRSs) derived from general population, genome-wide association study, cancer loci identified survivors of European ancestry at increased risk of subsequent basal cell carcinoma (odds ratio per s.d. of the PRS: OR = 1.37, 95% confidence interval (CI) = 1.29-1.46), female breast cancer (OR = 1.42, 95% CI = 1.27-1.58), thyroid cancer (OR = 1.48, 95% CI = 1.31-1.67), squamous cell carcinoma (OR = 1.20, 95% CI = 1.00-1.44) and melanoma (OR = 1.60, 95% CI = 1.31-1.96); however, the association for colorectal cancer was not significant (OR = 1.19, 95% CI = 0.94-1.52). An investigation of joint associations between PRSs and radiotherapy found more than additive increased risks of basal cell carcinoma, and breast and thyroid cancers. For survivors with radiotherapy exposure, the cumulative incidence of subsequent cancer by age 50 years was increased for those with high versus low PRS. These findings suggest a degree of shared genetic etiology for these malignancy types in the general population and survivors, which remains evident in the context of strong radiotherapy-related risk.

Radiation Therapy Technology Advances and Mitigation of Subsequent Neoplasms in Childhood Cancer Survivors

PURPOSE

In this Pediatric Normal Tissue Effects in the Clinic (PENTEC) vision paper, challenges and opportunities in the assessment of subsequent neoplasms (SNs) from radiation therapy (RT) are presented and discussed in the context of technology advancement.

METHODS AND MATERIALS

The paper discusses the current knowledge of SN risks associated with historic, contemporary, and future RT technologies. Opportunities for research and SN mitigation strategies in pediatric patients with cancer are reviewed.

RESULTS

Present experience with radiation carcinogenesis is from populations exposed during widely different scenarios. Knowledge gaps exist within clinical cohorts and follow-up; dose-response and volume effects; dose-rate and fractionation effects; radiation quality and proton/particle therapy; age considerations; susceptibility of specific tissues; and risks related to genetic predisposition. The biological mechanisms associated with local and patient-level risks are largely unknown.

CONCLUSIONS

Future cancer care is expected to involve several available RT technologies, necessitating evidence and strategies to assess the performance of competing treatments. It is essential to maximize the utilization of existing follow-up while planning for prospective data collection, including standardized registration of individual treatment information with linkage across patient databases.

Mortality After Major Cardiovascular Events in Survivors of Childhood Cancer

BACKGROUND

Adult survivors of childhood cancer are at risk for cardiovascular events.

OBJECTIVES

In this study, we sought to determine the risk for mortality after a major cardiovascular event among childhood cancer survivors compared with noncancer populations.

METHODS

All-cause and cardiovascular cause-specific mortality risks after heart failure (HF), coronary artery disease (CAD), or stroke were compared among survivors and siblings in the Childhood Cancer Survivor Study (CCSS) and participants in the Coronary Artery Risk Development in Young Adults (CARDIA) study. Cox proportional hazard regression models were used to estimate HRs and 95% CIs between groups, adjusted for demographic and clinical factors.

RESULTS

Among 25,658 childhood cancer survivors (median age at diagnosis 7 years, median age at follow-up or death 38 years) and 5,051 siblings, 1,780 survivors and 91 siblings had a cardiovascular event. After HF, CAD, and stroke, 10-year all-cause mortalities were 30% (95% CI: 26%-33%), 36% (95% CI: 31%-40%), and 29% (95% CI: 24%-33%), respectively, among survivors vs 14% (95% CI: 0%-25%), 14% (95% CI: 2%-25%), and 4% (95% CI: 0%-11%) among siblings. All-cause mortality risks among childhood cancer survivors were increased after HF (HR: 7.32; 95% CI: 2.56-20.89), CAD (HR: 5.54; 95% CI: 2.37-12.93), and stroke (HR: 3.57; 95% CI: 1.12-11.37). CAD-specific mortality risk was increased (HR: 3.70; 95% CI: 1.05-13.02). Among 5,114 CARDIA participants, 345 had a major event. Although CARDIA participants were on average decades older at events (median age 57 years vs 31 years), mortality risks were similar, except that all-cause mortality after CAD was significantly increased among childhood cancer survivors (HR: 1.85; 95% CI: 1.16-2.95).

CONCLUSIONS

Survivors of childhood cancer represent a population at high risk for mortality after major cardiovascular events.

Evolving therapies, neurocognitive outcomes, and functional independence in adult survivors of childhood glioma

BACKGROUND

Treatment of childhood glioma has evolved to reduce radiotherapy exposure with the goal of limiting late toxicity. However, the associations between treatment changes and neurocognition, and the contribution of neurocognition and chronic health conditions to attainment of adult independence, remain unknown.

METHODS

Adult survivors of childhood glioma diagnosed in 1970-1999 in the Childhood Cancer Survivor Study (n = 1284; median [minimum-maximum] 30 [18-51] years of age at assessment; 22 [15-34] years from diagnosis) self-reported neurocognitive impairment and chronic health conditions. Multivariable models evaluated associations between changes in treatment exposures (surgery only, chemotherapy [with or without surgery], cranial radiation [with or without chemotherapy and/or surgery]), and neurocognitive impairment. Latent class analysis with 5 indicators (employment, independent living, assistance with routine and/or personal care needs, driver's license, marital or partner status) identified classes of functional independence. Path analysis tested associations among treatment exposures, neurocognitive impairment, chronic health conditions, and functional independence. Statistical tests were 2-sided.

RESULTS

Cranial radiation exposure decreased over time (51%, 1970s; 46%, 1980s; 27%, 1990s]. However, compared with siblings, survivors with any treatment exposure were at elevated risk for neurocognitive impairment, including surgery only (eg, memory: relative risk = 2.22; task efficiency: relative risk = 1.88; both P < .001). Three classes of functional independence were identified: independent (58%), moderately independent (20%), and nonindependent (22%). Cranial radiation was associated with nonindependence through impaired task efficiency (β = 0.06), sensorimotor (β = 0.06), and endocrine (β = 0.10) chronic health conditions and through the associations between these conditions and task efficiency (each β = 0.04). Sensorimotor and endocrine chronic health conditions were associated with nonindependence through memory.

CONCLUSION

Most long-term glioma survivors achieve adult independence. However, functional nonindependence is associated with treatment-related neurocognitive impairment and chronic health conditions.

Neurologic morbidity and functional independence in adult survivors of childhood cancer

OBJECTIVE

To examine associations between neurologic late effects and attainment of independence in adult survivors of childhood cancer treated with central nervous system (CNS)-directed therapies.

METHODS

A total of 7881 survivors treated with cranial radiation therapy (n = 4051; CRT) and/or intrathecal methotrexate (n = 4193; IT MTX) ([CNS-treated]; median age [range] = 25.5 years [18-48]; time since diagnosis = 17.7 years [6.8-30.2]) and 8039 without CNS-directed therapy reported neurologic conditions including stroke, seizure, neurosensory deficits, focal neurologic dysfunction, and migraines/severe headaches. Functional independence was assessed using latent class analysis with multiple indicators (independent living, assistance with routine and personal care needs, ability to work/attend school, attainment of driver's license, marital/partner status). Multivariable regression models, adjusted for age, sex, race/ethnicity, and chronic health conditions, estimated odds ratios (OR) or relative risks (RR) for associations between neurologic morbidity, functional independence, and emotional distress.

RESULTS

Among CNS-treated survivors, three classes of independence were identified: (1) moderately independent, never married, and non-independent living (78.7%); (2) moderately independent, unable to drive (15.6%); and (3) non-independent (5.7%). In contrast to 50% of non-CNS-treated survivors and 60% of siblings, a fourth fully independent class of CNS-treated survivors was not identified. History of stroke (OR = 2.50, 95% CI: 1.70-3.68), seizure (OR = 9.70, 95% CI: 7.37-12.8), neurosensory deficits (OR = 2.67, 95% CI: 2.16-3.31), and focal neurologic dysfunction (OR = 3.05, 95% CI: 2.40-3.88) were associated with non-independence among CNS-treated survivors. Non-independence was associated with emotional distress symptoms.

INTERPRETATION

CNS-treated survivors do not attain full independence comparable to non-CNS-treated survivors or siblings. Interventions to promote independence may be beneficial for survivors with treatment-related neurological sequalae.

Development and validation of age-specific risk prediction models for primary ovarian insufficiency in long-term survivors of childhood cancer: a report from the Childhood Cancer Survivor Study and St Jude Lifetime Cohort

BACKGROUND

Female survivors of childhood cancer are at risk for primary ovarian insufficiency (POI), defined as the cessation of gonadal function before the age of 40 years. We aimed to develop and validate models to predict age-specific POI risk among long-term survivors of childhood cancer.

METHODS

To develop models to predict age-specific POI risk for the ages of 21-40 years, we used data from the Childhood Cancer Survivor Study (CCSS). Female survivors aged 18 years or older at their latest follow-up, with self-reported menstrual history information and free of subsequent malignant neoplasms within 5 years of diagnosis, were included. We evaluated models that used algorithms based on statistical or machine learning to consider all predictors, including cancer treatments. Cross-validated prediction performance metrics (eg, area under the receiver operating characteristic curve [AUROC]) were compared to select the best-performing models. For external validation of the models, we used data from 5-year survivors in the St Jude Lifetime Cohort (SJLIFE) with ovarian status clinically ascertained using hormone measurements (menopause defined by follicle stimulating hormone >30 mIU/mL and oestradiol <17 pg/mL) and medical chart or questionnaire review. We also evaluated an SJLIFE-based polygenic risk score for POI among 1985 CCSS survivors with genotype data available.

FINDINGS

7891 female CCSS survivors (922 with POI) were included in the development of the POI risk prediction model, and 1349 female SJLIFE survivors (101 with POI) were included in the validation study. Median follow-up from cancer diagnosis was 23·7 years (IQR 18·3-30·0) in CCSS and 15·1 years (10·4-22·9) in SJLIFE. Between the ages of 21 and 40 years, POI prevalence increased from 7·9% (95% CI 7·3-8·5) to 18·6% (17·3-20·0) in CCSS and 7·3% (5·8-8·9) to 14·9% (11·6-19·1) in SJLIFE. Age-specific logistic regression models considering ovarian radiation dosimetry or prescribed pelvic and abdominal radiation dose, along with individual chemotherapy predictors, performed well in CCSS. In the SJLIFE validation, the prescribed radiation dose model performed well (AUROC 0·88-0·95), as did a simpler model that considered any exposures to pelvic or abdominal radiotherapy or alkylators (0·82-0·90). Addition of the polygenic risk predictor significantly improved the average positive predictive value (from 0·76 [95% CI 0·63-0·89] to 0·87 [0·80-0·94]; p=0·029) among CCSS survivors treated with ovarian radiation and chemotherapy.

INTERPRETATION

POI risk prediction models using treatment information showed robust prediction performance in adult survivors of childhood cancer.

FUNDING

Canadian Institutes of Health Research, US National Cancer Institute.

A User's Guide and Summary of Pediatric Normal Tissue Effects in the Clinic (PENTEC): Radiation Dose-Volume Response for Adverse Effects After Childhood Cancer Therapy and Future Directions

Pediatric Normal Tissue Effects in the Clinic (PENTEC) is an international multidisciplinary effort that aims to summarize normal-tissue toxicity risks based on published dose-volume data from studies of children and adolescents treated with radiation therapy (RT) for cancer. With recognition that children are uniquely vulnerable to treatment-related toxic effects, our mission and challenge was to assemble our group of physicians (radiation and pediatric oncologists, subspecialists), physicists with clinical and modeling expertise, epidemiologists, and other scientists to develop evidence-based radiation dosimetric guidelines, as affected by developmental status and other factors (eg, other cancer therapies and host factors). These quantitative toxicity risk estimates could serve to inform RT planning and thereby improve outcomes. Tandem goals included the description of relevant medical physics issues specific to pediatric RT and the proposal of dose-volume outcome reporting standards to inform future studies. We created 19 organ-specific task forces and methodology to unravel the wealth of data from heterogeneous published studies. This report provides a high-level summary of PENTEC's genesis, methods, key findings, and associated concepts that affected our work and an explanation of how our findings may be interpreted and applied in the clinic. We acknowledge our predecessors in these efforts, and we pay homage to the children whose lives informed us and to future generations who we hope will benefit from this additional step in our path forward.

Trends in physical functioning in acute lymphoblastic leukemia and non-Hodgkin lymphoma survivors across three decades

PURPOSE

The impact of changes in therapy for childhood acute lymphoblastic leukemia (ALL) and non-Hodgkin lymphoma (NHL) on the prevalence of physical performance limitations and participation restrictions among survivors is unknown. We aimed to describe the prevalence of reduced function among ALL and NHL survivors by treatment era.

METHODS

Participants included survivors of childhood ALL and NHL, and a cohort of their siblings, participating in the Childhood Cancer Survivor Study (CCSS). Physical function was measured using questionnaire. The prevalence of reduced function was compared to siblings using generalized estimating equations, overall and stratified by treatment decade. Associations between organ system-specific chronic conditions (CTCAE v4.03) and function were also evaluated.

RESULTS

Among 6511 survivors (mean age 25.9 years (standard deviation 6.5)) and 4127 siblings, risk of performance limitations (15.2% vs. 12.5%, prevalence ratio [PR] = 1.5, 95%CI = 1.3-1.6), restrictions in personal care (2.0% vs. 0.6%, PR = 3.1, 95% CI = 2.0-4.8), routine activities (5.5% vs. 1.6%, PR = 3.6, 95% CI = 2.7-4.8), and work/school attendance (8.8% vs. 2.1%, PR = 4.5, 95% CI = 3.6-5.7) was increased in survivors vs. siblings. The prevalence of survivors reporting reduced function did not decrease between the 1970s and 1990s. The presence of neurological and cardiovascular conditions was associated with reduced function regardless of treatment decade.

CONCLUSIONS

Despite changes in therapy, the prevalence of poor physical function remained constant between the 1970s and 1990s. The CCSS clinical trial registration number is NCT01120353 (registered May 6, 2010).

IMPLICATIONS FOR CANCER SURVIVORS

Our findings support screening for reduced physical function so that early interventions to improve physical performance and mitigate chronic disease can be initiated.

Deep learning-based dose prediction to improve the plan quality of volumetric modulated arc therapy for gynecologic cancers

BACKGROUND

In recent years, deep-learning models have been used to predict entire three-dimensional dose distributions. However, the usability of dose predictions to improve plan quality should be further investigated.

PURPOSE

To develop a deep-learning model to predict high-quality dose distributions for volumetric modulated arc therapy (VMAT) plans for patients with gynecologic cancer and to evaluate their usability in driving plan quality improvements.

METHODS

A total of 79 VMAT plans for the female pelvis were used to train (47 plans), validate (16 plans), and test (16 plans) 3D dense dilated U-Net models to predict 3D dose distributions. The models received the normalized CT scan, dose prescription, and target and normal tissue contours as inputs. Three models were used to predict the dose distributions for plans in the test set. A radiation oncologist specializing in the treatment of gynecologic cancers scored the test set predictions using a 5-point scale (5, acceptable as-is; 4, prefer minor edits; 3, minor edits needed; 2, major edits needed; and 1, unacceptable). The clinical plans for which the dose predictions indicated that improvements could be made were reoptimized with constraints extracted from the predictions.

RESULTS

The predicted dose distributions in the test set were of comparable quality to the clinical plans. The mean voxel-wise dose difference was -0.14 ± 0.46 Gy. The percentage dose differences in the predicted target metrics ofD 1 % ${D}_{1{\mathrm{\% }}}$ andD 98 % ${D}_{98{\mathrm{\% }}}$ were -1.05% ± 0.59% and 0.21% ± 0.28%, respectively. The dose differences in the predicted organ at risk mean and maximum doses were -0.30 ± 1.66 Gy and -0.42 ± 2.07 Gy, respectively. A radiation oncologist deemed all of the predicted dose distributions clinically acceptable; 12 received a score of 5, and four received a score of 4. Replanning of flagged plans (five plans) showed that the original plans could be further optimized to give dose distributions close to the predicted dose distributions.

CONCLUSIONS

Deep-learning dose prediction can be used to predict high-quality and clinically acceptable dose distributions for VMAT female pelvis plans, which can then be used to identify plans that can be improved with additional optimization.

Testicular Dysfunction in Male Childhood Cancer Survivors Treated With Radiation Therapy: A PENTEC Comprehensive Review

PURPOSE

The male reproductive task force of the Pediatric Normal Tissue Effects in the Clinic (PENTEC) initiative performed a comprehensive review that included a meta-analysis of publications reporting radiation dose-volume effects for risk of impaired fertility and hormonal function after radiation therapy for pediatric malignancies.

METHODS AND MATERIALS

The PENTEC task force conducted a comprehensive literature search to identify published data evaluating the effect of testicular radiation dose on reproductive complications in male childhood cancer survivors. Thirty-one studies were analyzed, of which 4 had testicular dose data to generate descriptive scatter plots. Two cohorts were identified. Cohort 1 consisted of pediatric and young adult patients with cancer who received scatter radiation therapy to the testes. Cohort 2 consisted of pediatric and young adult patients with cancer who received direct testicular radiation therapy as part of their cancer therapy. Descriptive scatter plots were used to delineate the relationship between the effect of mean testicular dose on sperm count reduction, testosterone, follicle stimulating hormone (FSH), and luteinizing hormone (LH) levels.

RESULTS

Descriptive scatter plots demonstrated a 44% to 80% risk of oligospermia when the mean testicular dose was <1 Gy, but this was recovered by >12 months in 75% to 100% of patients. At doses >1 Gy, the rate of oligospermia increased to >90% at 12 months. Testosterone levels were generally not affected when the mean testicular dose was <0.2 Gy but were abnormal in up to 25% of patients receiving between 0.2 and 12 Gy. Doses between 12 and 19 Gy may be associated with abnormal testosterone in 40% of patients, whereas doses >20 Gy to the testes were associated with a steep increase in abnormal testosterone in at least 68% of patients. FSH levels were unaffected by a mean testicular dose <0.2 Gy, whereas at doses >0.5 Gy, the risk was between 40% and 100%. LH levels were affected at doses >0.5 Gy in 33% to 75% of patients between 10 and 24 months after radiation. Although dose modeling could not be performed in cohort 2, the risk of reproductive toxicities was escalated with doses >10 Gy.

CONCLUSIONS

This PENTEC comprehensive review demonstrates important relationships between scatter or direct radiation dose on male reproductive endpoints including semen analysis and levels of FSH, LH, and testosterone.

Trends in Radiation Dose to the Contralateral Breast During Breast Cancer Radiation Therapy

Over 4 million survivors of breast cancer live in the United States, 35% of whom were treated before 2009. Approximately half of patients with breast cancer receive radiation therapy, which exposes the untreated contralateral breast to radiation and increases the risk of a subsequent contralateral breast cancer (CBC). Radiation oncology has strived to reduce unwanted radiation dose, but it is unknown whether a corresponding decline in actual dose received to the untreated contralateral breast has occurred. The purpose of this study was to evaluate trends in unwanted contralateral breast radiation dose to inform risk assessment of second primary cancer in the contralateral breast for long-term survivors of breast cancer. Individually estimated radiation absorbed doses to the four quadrants and areola central area of the contralateral breast were estimated for 2,132 women treated with radiation therapy for local/regional breast cancers at age <55 years diagnosed between 1985 and 2008. The two inner quadrant doses and two outer quadrant doses were averaged. Trends in dose to each of the three areas of the contralateral breast were evaluated in multivariable models. The population impact of reducing contralateral breast dose on the incidence of radiation-associated CBC was assessed by estimating population attributable risk fraction (PAR) in a multivariable model. The median dose to the inner quadrants of the contralateral breast was 1.70 Gy; to the areola, 1.20 Gy; and to the outer quadrants, 0.72 Gy. Ninety-two percent of patients received ≥1 Gy to the inner quadrants. For each calendar year of diagnosis, dose declined significantly for each location, most rapidly for the inner quadrants (0.04 Gy/year). Declines in dose were similar across subgroups defined by age at diagnosis and body mass index. The PAR for CBC due to radiation exposure >1 Gy for women <40 years of age was 17%. Radiation dose-reduction measures have reduced dose to the contralateral breast during breast radiation therapy. Reducing the dose to the contralateral breast to <1 Gy could prevent an estimated 17% of subsequent radiation-associated CBCs for women treated under 40 years of age. These dose estimates inform CBC surveillance for the growing number of breast cancer survivors who received radiation therapy as young women in recent decades. Continued reductions in dose to the contralateral breast could further reduce the incidence of radiation-associated CBC.

Polygenic Risk and Chemotherapy-Related Subsequent Malignancies in Childhood Cancer Survivors: A Childhood Cancer Survivor Study and St Jude Lifetime Cohort Study Report

PURPOSE

Chemotherapeutic exposures are associated with subsequent malignant neoplasm (SMN) risk. The role of genetic susceptibility in chemotherapy-related SMNs should be defined as use of radiation therapy (RT) decreases.

PATIENTS AND METHODS

SMNs among long-term childhood cancer survivors of European (EUR; N = 9,895) and African (AFR; N = 718) genetic ancestry from the Childhood Cancer Survivor Study and St Jude Lifetime Cohort Study were evaluated. An externally validated 179-variant polygenic risk score (PRS) associated with pleiotropic adult cancer risk from the UK Biobank Study (N > 400,000) was computed for each survivor. SMN cumulative incidence comparing top and bottom PRS quintiles was estimated, along with hazard ratios (HRs) from proportional hazards models.

RESULTS

A total of 1,594 survivors developed SMNs, with basal cell carcinomas (n = 822), breast cancers (n = 235), and thyroid cancers (n = 221) being the most frequent. Although SMN risk associations with the PRS were extremely modest in RT-exposed EUR survivors (HR, 1.22; P = .048; n = 4,630), the increase in 30-year SMN cumulative incidence and HRs comparing top and bottom PRS quintiles was statistically significant among nonirradiated EUR survivors (n = 4,322) treated with alkylating agents (17% v 6%; HR, 2.46; P < .01), anthracyclines (20% v 8%; HR, 2.86; P < .001), epipodophyllotoxins (23% v 1%; HR, 12.20; P < .001), or platinums (46% v 7%; HR, 8.58; P < .01). This PRS also significantly modified epipodophyllotoxin-related SMN risk among nonirradiated AFR survivors (n = 414; P < .01). Improvements in prediction attributable to the PRS were greatest for epipodophyllotoxin-exposed (AUC, 0.71 v 0.63) and platinum-exposed (AUC,0.68 v 0.58) survivors.

CONCLUSION

A pleiotropic cancer PRS has strong potential for improving SMN clinical risk stratification among nonirradiated survivors treated with specific chemotherapies. A polygenic risk screening approach may be a valuable complement to an early screening strategy on the basis of treatments and rare cancer-susceptibility mutations.

Subsequent female breast cancer risk associated with anthracycline chemotherapy for childhood cancer

Anthracycline-based chemotherapy is associated with increased subsequent breast cancer (SBC) risk in female childhood cancer survivors, but the current evidence is insufficient to support early breast cancer screening recommendations for survivors treated with anthracyclines. In this study, we pooled individual patient data of 17,903 survivors from six well-established studies, of whom 782 (4.4%) developed a SBC, and analyzed dose-dependent effects of individual anthracycline agents on developing SBC and interactions with chest radiotherapy. A dose-dependent increased SBC risk was seen for doxorubicin (hazard ratio (HR) per 100 mg m-2: 1.24, 95% confidence interval (CI): 1.18-1.31), with more than twofold increased risk for survivors treated with ≥200 mg m-2 cumulative doxorubicin dose versus no doxorubicin (HR: 2.50 for 200-299 mg m-2, HR: 2.33 for 300-399 mg m-2 and HR: 2.78 for ≥400 mg m-2). For daunorubicin, the associations were not statistically significant. Epirubicin was associated with increased SBC risk (yes/no, HR: 3.25, 95% CI: 1.59-6.63). For patients treated with or without chest irradiation, HRs per 100 mg m-2 of doxorubicin were 1.11 (95% CI: 1.02-1.21) and 1.26 (95% CI: 1.17-1.36), respectively. Our findings support that early initiation of SBC surveillance may be reasonable for survivors who received ≥200 mg m-2 cumulative doxorubicin dose and should be considered in SBC surveillance guidelines for survivors and future treatment protocols.

Cardiovascular Risk Factor Disparities in Adult Survivors of Childhood Cancer Compared With the General Population

Background

It is unknown whether a history of childhood cancer modifies the established disparities in cardiovascular risk factors (CVRFs) observed in the general population.

Objectives

We sought to determine if disparities in CVRFs by race/ethnicity are similar among childhood cancer survivors compared with the general population.

Methods

The Childhood Cancer Survivor Study (CCSS) is a retrospective cohort with a longitudinal follow-up of 24,084 5-year survivors diagnosed between 1970 and 1999. Multivariable piecewise exponential regression estimated incidence rate ratios (IRRs) for hypertension, hyperlipidemia, diabetes, obesity, and ≥2 CVRFs by race/ethnicity. The CCSS sibling cohort and the National Health and Nutrition Examination Survey cohort were used to compare the sociodemographic-adjusted IRRs for same-race/same-ethnicity disparities.

Results

Non-Hispanic Black (NHB) (n = 1,092) and Hispanic (n = 1,405) survivors compared with non-Hispanic White (NHW) (n = 13,960) survivors reported a higher cumulative incidence of diabetes (8.4%, 9.7%, and 5.1%, respectively); obesity (47.2%, 48.9%, and 30.2%, respectively); multiple CVRFs (17.7%, 16.6%, and 12.3%, respectively); and, for NHB survivors, hypertension (19.5%, 13.6%, and 14.3%, respectively) by 40 years of age (P < 0.001). Controlling for sociodemographic and treatment factors compared with NHW survivors, IRRs for NHB were increased for hypertension (IRR: 1.4; 95% CI: 1.1-1.8), obesity (IRR: 1.7; 95% CI: 1.4-2.1), and multiple CVRFs (IRR: 1.6; 95% CI: 1.2-2.1). IRRs for Hispanic survivors were increased for diabetes (IRR: 1.8; 95% CI: 1.2-2.6) and obesity (IRR: 1.4; 95% CI: 1.2-1.7). The pattern of IRRs for CVRF differences was similar among CCSS sibling and National Health and Nutrition Examination Survey cohorts.

Conclusions

The higher burden of CVRFs among NHB and Hispanic survivors compared with NHW survivors was similar to the general population. The promotion of cardiovascular health equity is critical in this high-risk population.

Cardiac Substructure Radiation Dose and Risk of Late Cardiac Disease in Survivors of Childhood Cancer: A Report From the Childhood Cancer Survivor Study

PURPOSE

Radiation-associated cardiac disease is a major cause of morbidity/mortality among childhood cancer survivors. Radiation dose-response relationships for cardiac substructures and cardiac diseases remain unestablished.

METHODS

Using the 25,481 5-year survivors of childhood cancer treated from 1970 to 1999 in the Childhood Cancer Survivor Study, we evaluated coronary artery disease (CAD), heart failure (HF), valvular disease (VD), and arrhythmia. We reconstructed radiation doses for each survivor to the coronary arteries, chambers, valves, and whole heart. Excess relative rate (ERR) models and piecewise exponential models evaluated dose-response relationships.

RESULTS

The cumulative incidence 35 years from diagnosis was 3.9% (95% CI, 3.4 to 4.3) for CAD, 3.8% (95% CI, 3.4 to 4.2) for HF, 1.2% (95% CI, 1.0 to 1.5) for VD, and 1.4% (95% CI, 1.1 to 1.6) for arrhythmia. A total of 12,288 survivors (48.2%) were exposed to radiotherapy. Quadratic ERR models improved fit compared with linear ERR models for the dose-response relationship between mean whole heart and CAD, HF, and arrhythmia, suggesting a potential threshold dose; however, such departure from linearity was not observed for most cardiac substructure end point dose-response relationships. Mean doses of 5-9.9 Gy to the whole heart did not increase the risk of any cardiac diseases. Mean doses of 5-9.9 Gy to the right coronary artery (rate ratio [RR], 2.6 [95% CI, 1.6 to 4.1]) and left ventricle (RR, 2.2 [95% CI, 1.3 to 3.7]) increased risk of CAD, and to the tricuspid valve (RR, 5.5 [95% CI, 2.0 to 15.1]) and right ventricle (RR, 8.4 [95% CI, 3.7 to 19.0]) increased risk of VD.

CONCLUSION

Among children with cancer, there may be no threshold dose below which radiation to the cardiac substructures does not increase the risk of cardiac diseases. This emphasizes their importance in modern treatment planning.

Liver Late Effects in Childhood Cancer Survivors Treated With Radiation Therapy: A PENTEC Comprehensive Review

PURPOSE

A pediatric normal tissue effects in the clinic (PENTEC) comprehensive review of patients with childhood cancer who received radiation therapy (RT) to the liver was performed to develop models that may inform RT dose constraints for the liver and improve risk forecasting of toxicities.

METHODS AND MATERIALS

A systematic literature search was performed to identify published data on hepatic toxicities in children. Treatment and outcome data were extracted and used to generate normal tissue complication probability (NTCP) models. Complications from both whole and partial liver irradiation were considered. For whole liver irradiation, total body irradiation and non-total body irradiation treatments were considered, but it was assumed that the entire liver received the prescribed dose. For partial liver irradiation, only Wilms tumor flank field RT could be analyzed. However, a prescribed dose assumption could not be applied, and there was a paucity of analyzable liver dosimetry data. To associate the dose-volume exposures with the partial volume complication data from flank irradiation, liver dose-volume metrics were reconstructed for Wilms tumor flank RT using age-specific computational phantoms as a function of field laterality and superior extent of the field.

RESULTS

The literature search identified 2103 investigations pertaining to hepatic sinusoidal obstructive syndrome (SOS) and liver failure in pediatric patients. All abstracts were screened, and 241 articles were reviewed in full by the study team. A model was developed to calculate the risk of developing SOS after whole liver RT. RT dose (P = .006) and receipt of nonalkylating chemotherapy (P = .01) were significant. Age <20 years at time of RT was borderline significant (P = .058). The model predicted a 2% risk of SOS with zero RT dose, 6.1% following 10 Gy, and 14.5% following 20 Gy to the whole liver (modeled as the linear-quadratic equivalent dose in 2-Gy fractions [α/β = 3 Gy]). Patients with Wilms tumor treated with right flank RT had a higher observed rate of SOS than patients receiving left flank RT, but data were insufficient to generate an NTCP model for partial liver irradiation. From the phantom-based dose reconstructions, mean liver dose was estimated to be 2.16 ± 1.15 Gy and 6.54 ± 2.50 Gy for left and right flank RT, respectively, using T10-T11 as the superior field border and a prescription dose of 10.8 Gy (based on dose reconstruction). Data were sparse regarding rates of late liver injury after RT, which suggests low rates of severe toxicity after treatment for common pediatric malignancies.

CONCLUSIONS

This pediatric normal tissue effects in the clinic (PENTEC) review provides an NTCP model to estimate the risk of hepatic SOS as a function of RT dose following whole liver RT and quantifies the range of mean liver doses from typical Wilms tumor flank irradiation fields. Patients treated with right flank RT had higher rates of SOS than patients treated with left flank RT, but data were insufficient to develop a model for partial liver irradiation. Risk of SOS was estimated to be approximately ≤6% in pediatric patients receiving whole liver doses of <10 Gy.

Cumulative burden of late, major surgical intervention in survivors of childhood cancer: a report from the Childhood Cancer Survivor Study (CCSS) cohort

BACKGROUND

Multimodal cancer therapy places childhood cancer survivors at increased risk for chronic health conditions, subsequent malignancies, and premature mortality as they age. We aimed to estimate the cumulative burden of late (>5 years from cancer diagnosis), major surgical interventions among childhood cancer survivors, compared with their siblings, and to examine associations between specific childhood cancer treatments and the burden of late surgical interventions.

METHODS

We analysed data from the Childhood Cancer Survivor Study (CCSS), a retrospective cohort study with longitudinal prospective follow-up of 5-year survivors of childhood cancer (diagnosed before age 21 years) treated at 31 institutions in the USA, with a comparison group of nearest-age siblings of survivors selected by simple random sampling. The primary outcome was any self-reported late, major surgical intervention (defined as any anaesthesia-requiring operation) occurring 5 years or more after the primary cancer diagnosis. The cumulative burden was assessed with mean cumulative counts (MCC) of late, major surgical interventions. Piecewise exponential regression models with calculation of adjusted rate ratios (RRs) evaluated associations between treatment exposures and late, major surgical interventions.

FINDINGS

Between Jan 1, 1970, and Dec 31, 1999, 25 656 survivors were diagnosed (13 721 male, 11 935 female; median follow-up 21·8 years [IQR 16·5-28·4]; median age at diagnosis 6·1 years [3·0-12·4]); 5045 nearest-age siblings were also included as a comparison group. Survivors underwent 28 202 late, major surgical interventions and siblings underwent 4110 late, major surgical interventions. The 35-year MCC of a late, major surgical intervention was 206·7 per 100 survivors (95% CI 202·7-210·8) and 128·9 per 100 siblings (123·0-134·7). The likelihood of a late, major surgical intervention was higher in survivors versus siblings (adjusted RR 1·8, 95% CI 1·7-1·9) and in female versus male survivors (1·4; 1·4-1·5). Survivors diagnosed in the 1990s (adjusted RR 1·4, 95% CI 1·3-1·5) had an increased likelihood of late surgery compared with those diagnosed in the 1970s. Survivors received late interventions more frequently than siblings in most anatomical regions or organ systems, including CNS (adjusted RR 16·9, 95% CI 9·4-30·4), endocrine (6·7, 5·2-8·7), cardiovascular (6·6, 5·2-8·3), respiratory (5·3, 3·4-8·2), spine (2·4, 1·8-3·2), breast (2·1, 1·7-2·6), renal or urinary (2·0, 1·5-2·6), musculoskeletal (1·5, 1·4-1·7), gastrointestinal (1·4, 1·3-1·6), and head and neck (1·2, 1·1-1·4) interventions. Survivors of Hodgkin lymphoma (35-year MCC 333·3 [95% CI 320·1-346·6] per 100 survivors), Ewing sarcoma (322·9 [294·5-351·3] per 100 survivors), and osteosarcoma (269·6 [250·1-289·2] per 100 survivors) had the highest cumulative burdens of late, major surgical interventions. Locoregional surgery or radiotherapy cancer treatment were associated with undergoing late surgical intervention in the same body region or organ system.

INTERPRETATION

Childhood cancer survivors have a significant burden of late, major surgical interventions, a late effect that has previously been poorly quantified. Survivors would benefit from regular health-care evaluations aiming to anticipate impending surgical issues and to intervene early in the disease course when feasible.

FUNDING

US National Institutes of Health, US National Cancer Institute, American Lebanese Syrian Associated Charities, and St Jude Children's Research Hospital.

Late Health Outcomes Among Survivors of Wilms Tumor Diagnosed Over Three Decades: A Report From the Childhood Cancer Survivor Study

PURPOSE

To evaluate long-term morbidity and mortality among unilateral, nonsyndromic Wilms tumor (WT) survivors according to conventional treatment regimens.

METHODS

Cumulative incidence of late mortality (≥ 5 years from diagnosis) and chronic health conditions (CHCs) were evaluated in WT survivors from the Childhood Cancer Survivor Study. Outcomes were evaluated by treatment, including nephrectomy combined with vincristine and actinomycin D (VA), VA + doxorubicin + abdominal radiotherapy (VAD + ART), VAD + ART + whole lung radiotherapy, or receipt of ≥ 4 chemotherapy agents.

RESULTS

Among 2,008 unilateral WT survivors, 142 deaths occurred (standardized mortality ratio, 2.9, 95% CI, 2.5 to 3.5; 35-year cumulative incidence of death, 7.8%, 95% CI, 6.3 to 9.2). The 35-year cumulative incidence of any grade 3-5 CHC was 34.1% (95% CI, 30.7 to 37.5; rate ratio [RR] compared with siblings 3.0, 95% CI, 2.6 to 3.5). Survivors treated with VA alone had comparable risk for all-cause late mortality relative to the general population (standardized mortality ratio, 1.0; 95% CI, 0.5 to 1.7) and modestly increased risk for grade 3-5 CHCs compared with siblings (RR, 1.5; 95% CI, 1.1 to 2.0), but remained at increased risk for intestinal obstruction (RR, 9.4; 95% CI, 3.9 to 22.2) and kidney failure (RR, 11.9; 95% CI, 4.2 to 33.6). Magnitudes of risk for grade 3-5 CHCs, including intestinal obstruction, kidney failure, premature ovarian insufficiency, and heart failure, increased by treatment group intensity.

CONCLUSION

With approximately 40% of patients with newly diagnosed WT currently treated with VA alone, the burden of late mortality/morbidity in future decades is projected to be lower than that for survivors from earlier eras. Nevertheless, the risk of late effects such as intestinal obstruction and kidney failure was elevated across all treatment groups, and there was a dose-dependent increase in risk for all grade 3-5 CHCs by treatment group intensity.

Late-onset Cognitive Impairment and Modifiable Risk Factors in Adult Childhood Cancer Survivors

Importance

Long-term survivors of childhood cancer may be at elevated risk for new neurocognitive impairment and decline as they age into adulthood.

Objective

To determine whether aging adult childhood cancer survivors report more new-onset neurocognitive impairments compared with their siblings and to identify risk factors associated with such impairments.

Design, Setting, and Participants

Participants of this cohort study included adult survivors of childhood cancer from the Childhood Cancer Survivor Study and their siblings as a control group. The original cohort included survivors who received a diagnosis between January 1, 1970, and December 31, 1986, for whom longitudinal neurocognitive assessment was available. This study examined the prevalence of new-onset neurocognitive impairment between baseline (23.4 years after diagnosis) and follow-up (35.0 years after diagnosis). The analysis was performed from January 2021 to May 2022.

Exposures

Cancer treatment exposures were abstracted from medical records. Chronic health conditions were graded using Common Terminology Criteria for Adverse Events version 4.03.

Main Outcomes and Measures

The primary outcome was new-onset (present at follow-up, but not present at baseline) neurocognitive impairment (defined as a score in the worst 10% of the sibling cohort). Impairment was assessed using the Childhood Cancer Survivor Study Neurocognitive questionnaire. Relative risks (RRs) and 95% CIs were used to estimate associations of neurocognitive impairment with treatment and health behaviors and conditions using generalized linear models.

Results

The cohort comprised 2375 survivors (mean [SD] age at evaluation, 31.8 [7.5] years; 1298 women [54.6%]) of childhood cancer, including acute lymphoblastic leukemia (ALL; 1316 participants), central nervous system (CNS) tumors (488 participants), and Hodgkin lymphoma (HL; 571 participants). A total of 232 siblings (mean [SD] age at evaluation, 34.2 [8.4] years; 134 women [57.8%]) were included. Compared with siblings, a higher proportion of survivors with no impairment in memory at baseline had new-onset memory impairment at follow-up: siblings proportion, 7.8% (95% CI, 4.3%-11.4%); ALL survivors treated with chemotherapy only, 14.0% (95% CI, 10.7%-17.4%); ALL survivors treated with cranial radiation (CRT), 25.8% (95% CI, 22.6%-29.0%); CNS tumor survivors, 34.7% (95% CI, 30.0%-39.5%); and HL survivors, 16.6% (95% CI, 13.4%-19.8%). New-onset memory impairment was associated with CRT in CNS tumor survivors (RR, 1.97; 95% CI, 1.33-2.90) and alkylator chemotherapy greater than or equal to 8000 mg/m2 in ALL survivors treated without CRT (RR, 2.80; 95% CI, 1.28-6.12). Neurologic conditions mediated the impact of CRT on new-onset memory impairment in CNS survivors. Smoking, low educational attainment, and low physical activity were associated with elevated risk for new-onset memory impairment.

Conclusions and Relevance

These findings suggest that adult survivors of childhood cancer are at elevated risk for late-onset memory impairment related to modifiable risk factors identified early in survivorship.

Specific causes of excess late mortality and association with modifiable risk factors among survivors of childhood cancer: a report from the Childhood Cancer Survivor Study cohort

BACKGROUND

5-year survival after childhood cancer does not fully describe life-years lost due to childhood cancer because there are a large number of deaths occurring beyond 5-years (late mortality) related to cancer and cancer treatment. Specific causes of health-related (non-recurrence, non-external) late mortality and risk reduction through modifiable lifestyle and cardiovascular risk factors are not well described. Through using a well-characterised cohort of 5-year survivors of the most common childhood cancers, we evaluated specific health-related causes of late mortality and excess deaths compared with the general US population and identified targets to reduce future risk.

METHODS

In this multi-institutional, hospital-based, retrospective cohort study, late mortality (death ≥5 years from diagnosis) and specific causes of death were evaluated in 34 230 5-year survivors of childhood cancer diagnosed at an age younger than 21 years from 1970 to 1999 at 31 institutions in the USA and Canada; median follow-up from diagnosis was 29 years (range 5-48) in the Childhood Cancer Survivor Study. Demographic, self-reported modifiable lifestyle (ie, smoking, alcohol, physical activity, and BMI) and cardiovascular risk factors (ie, hypertension, diabetes, and dyslipidaemia) associated with health-related mortality (which excludes death from primary cancer and external causes and includes death from late effects of cancer therapy) were evaluated.

FINDINGS

40-year cumulative all-cause mortality was 23·3% (95% CI 22·7-24·0), with 3061 (51·2%) of 5916 deaths from health-related causes. Survivors 40 years or more from diagnosis experienced 131 excess health-related deaths per 10 000 person-years (95% CI 111-163), including those due to the top three causes of health-related death in the general population: cancer (absolute excess risk per 10 000 person-years 54, 95% CI 41-68), heart disease (27, 18-38), and cerebrovascular disease (10, 5-17). Healthy lifestyle and absence of hypertension and diabetes were each associated with a 20-30% reduction in health-related mortality independent of other factors (all p values ≤0·002).

INTERPRETATION

Survivors of childhood cancer are at excess risk of late mortality even 40 years from diagnosis, due to many of the leading causes of death in the US population. Modifiable lifestyle and cardiovascular risk factors associated with reduced risk for late mortality should be part of future interventions.

FUNDING

US National Cancer Institute and the American Lebanese Syrian Associated Charities.

Development and Validation of a Prediction Model for Kidney Failure in Long-Term Survivors of Childhood Cancer

PURPOSE

Kidney failure is a rare but serious late effect following treatment for childhood cancer. We developed a model using demographic and treatment characteristics to predict individual risk of kidney failure among 5-year survivors of childhood cancer.

METHODS

Five-year survivors from the Childhood Cancer Survivor Study (CCSS) without history of kidney failure (n = 25,483) were assessed for subsequent kidney failure (ie, dialysis, kidney transplantation, or kidney-related death) by age 40 years. Outcomes were identified by self-report and linkage with the Organ Procurement and Transplantation Network and the National Death Index. A sibling cohort (n = 5,045) served as a comparator. Piecewise exponential models accounting for race/ethnicity, age at diagnosis, nephrectomy, chemotherapy, radiotherapy, congenital genitourinary anomalies, and early-onset hypertension estimated the relationships between potential predictors and kidney failure, using area under the curve (AUC) and concordance (C) statistic to evaluate predictive power. Regression coefficient estimates were converted to integer risk scores. The St Jude Lifetime Cohort Study and the National Wilms Tumor Study served as validation cohorts.

RESULTS

Among CCSS survivors, 204 developed late kidney failure. Prediction models achieved an AUC of 0.65-0.67 and a C-statistic of 0.68-0.69 for kidney failure by age 40 years. Validation cohort AUC and C-statistics were 0.88/0.88 for the St Jude Lifetime Cohort Study (n = 8) and 0.67/0.64 for the National Wilms Tumor Study (n = 91). Risk scores were collapsed to form statistically distinct low- (n = 17,762), moderate- (n = 3,784), and high-risk (n = 716) groups, corresponding to cumulative incidences in CCSS of kidney failure by age 40 years of 0.6% (95% CI, 0.4 to 0.7), 2.1% (95% CI, 1.5 to 2.9), and 7.5% (95% CI, 4.3 to 11.6), respectively, compared with 0.2% (95% CI, 0.1 to 0.5) among siblings.

CONCLUSION

Prediction models accurately identify childhood cancer survivors at low, moderate, and high risk for late kidney failure and may inform screening and interventional strategies.

Cardiac Disease in Childhood Cancer Survivors Treated With Radiation Therapy: A PENTEC Comprehensive Review

PURPOSE

Radiation therapy (RT) is an essential component in the treatment of many pediatric malignancies. Thoracic RT may expose the heart to radiation dose and thereby increase the risk of late cardiac disease. This comprehensive review from the Pediatric Normal Tissue Effects in the Clinic (PENTEC) initiative focused on late cardiac disease in survivors of childhood cancer treated with RT.

METHODS AND MATERIALS

This systematic review was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) methodology. We identified 1496 articles; 4 were included for dose-response modeling between mean cardiac radiation dose and risk of late coronary artery disease, heart failure (HF), valvular disease, and any cardiac disease.

RESULTS

For each 10-Gy increase in corrected mean cardiac radiation dose in 1.8- to 2.0-Gy fractions, we estimated a hazard ratio of 2.01 (95% confidence interval [CI], 1.79-2.25) for coronary artery disease, of 1.87 (95% CI, 1.70-2.06) for HF, of 1.87 (95% CI, 1.78-1.96) for valvular disease, and of 1.88 (95% CI, 1.75-2.03) for any cardiac disease. From the same model, for each 100-mg/m² increase in cumulative anthracycline dose, the hazard ratio for the development of HF was 1.93 (95% CI, 1.58-2.36), equivalent to an increase in mean heart dose of approximately 10.5 Gy. Other nontreatment factors were inconsistently reported in the analyzed articles.

CONCLUSIONS

Radiation dose to the heart increases the risk of late cardiac disease, but survivors of childhood cancer who receive a mean dose <10 Gy at standard fractionation are at low absolute risk (<∼2% approximately 30 years after exposure) of late cardiac disease in the absence of anthracycline exposure. Minimizing cardiac radiation dose is especially relevant in children receiving anthracyclines. When cardiac sparing is not possible, we recommend prioritizing target coverage. It is likely that individual cardiac substructure doses will be a better predictor of specific cardiac diseases than mean dose, and we urge the pediatric oncology community to further study these relationships.

Emotional, behavioral, and physical health consequences of loneliness in young adult survivors of childhood cancer: Results from the Childhood Cancer Survivor Study

BACKGROUND

Young adults in the general population are at risk of experiencing loneliness, which has been associated with physical and mental health morbidities. The prevalence and consequences of loneliness in young adult survivors of childhood cancer remain unknown.

METHODS

A total of 9664 young adult survivors of childhood cancer (median age at diagnosis 10.5 years [interquartile range (IQR), 5-15], 27.1 years at baseline [IQR, 23-32]) and 2221 siblings enrolled in the Childhood Cancer Survivor Study completed a self-reported survey question assessing loneliness on the Brief Symptom Inventory-18 at baseline and follow-up (median follow-up, 6.6 years). Multivariable models evaluated the prevalence of loneliness at baseline only, follow-up only, and baseline + follow-up, and its associations with emotional distress, health behaviors, and chronic conditions at follow-up.

RESULTS

Survivors were more likely than siblings to report loneliness at baseline + follow-up (prevalence ratio [PR] 2.2; 95% confidence interval [CI], 1.7-3.0) and at follow-up only (PR, 1.4; 95% CI, 1.1-1.7). Loneliness at baseline + follow-up was associated with elevated risk of anxiety (relative risk [RR], 9.8; 95% CI, 7.5-12.7), depression (RR, 17.9; 95% CI, 14.1-22.7), and current smoking (odds ratio [OR], 1.7; 95% CI, 1.3-2.3) at follow-up. Loneliness at follow-up only was associated with suicidal ideation (RR, 1.5; 95% CI, 1.1-2.1), heavy/risky alcohol consumption (RR, 1.3; 95% CI, 1.1-1.5), and new-onset grade 2-4 chronic conditions (RR, 1.3; 95% CI, 1.0-1.7).

CONCLUSIONS

Young adult survivors of childhood cancer have elevated risk of experiencing loneliness, which is associated with future emotional distress, risky health behaviors, and new-onset chronic conditions.

Long-Term Morbidity and Mortality Among Survivors of Neuroblastoma Diagnosed During Infancy: A Report From the Childhood Cancer Survivor Study

PURPOSE

To describe the risk of late mortality, subsequent malignant neoplasms (SMNs), and chronic health conditions (CHCs) in survivors of neuroblastoma diagnosed in infancy by treatment era and exposures.

METHODS

Among 5-year survivors of neuroblastoma in the Childhood Cancer Survivor Study diagnosed age < 1 year between 1970 and 1999, we examined the cumulative incidence of late (> 5 years from diagnosis) mortality, SMN, and CHCs (grades 2-5 and 3-5). Multivariable Cox regression models estimated hazard ratios (HRs) and 95% CIs by decade and treatment (surgery-alone v chemotherapy with or without surgery [C ± S] v radiation with or without chemotherapy ± surgery [R ± C ± S]) among survivors and between survivors and 5,051 siblings.

RESULTS

Among 1,397 eligible survivors, the 25-year cumulative incidence of late mortality was 2.1% (95% CI, 1.3 to 3.9) with no difference by treatment era. Among 990 participants who completed a baseline survey, fewer survivors received radiation in more recent eras (51.2% 1970s, 20.4% 1980s, and 10.1% 1990s; P < .001). Risk of SMN was elevated only among individuals treated with radiation-containing regimens compared with surgery alone (HR[C ± S], 3.2 [95% CI, 0.9 to 11.6]; HR[R ± C ± S], 5.7 [95% CI, 1.2 to 28.1]). In adjusted models, there was a 50% reduction in risk of grade 3-5 CHCs in the 1990s versus 1970s (HR, 0.5 [95% CI, 0.3 to 0.9]; P = .01); individuals treated with radiation had a 3.6-fold risk for grade 3-5 CHCs (95% CI, 2.1 to 6.2) versus those treated with surgery alone. When compared with siblings, risk of grade 3-5 CHCs for survivors was lowest in the most recent era (HR[1970s], 4.7 [95% CI, 3.4 to 6.5]; HR[1980s], 4.6 [95% CI, 3.3 to 6.4]; HR[1990s], 2.5 [95% CI, 1.7 to 3.9]).

CONCLUSION

Neuroblastoma survivors treated during infancy have a relatively low absolute burden of late mortality and SMN. Encouragingly, risk of CHCs has declined in more recent eras with reduced exposure to radiation therapy.

Physics Considerations for Evaluation of Dose for Dose-Response Models of Pediatric Late Effects From Radiation Therapy

PURPOSE

We describe the methods used to estimate the accuracy of dosimetric data found in literature sources used to construct the Pediatric Normal Tissue Effects in the Clinic (PENTEC) dose-response models, summarize these findings of each organ-specific task force, describe some of the dosimetric challenges and the extent to which these efforts affected the final modeling results, and provide guidance on the interpretation of the dose-response results given the various dosimetric uncertainties.

METHODS AND MATERIALS

Each of the PENTEC task force medical physicists reviewed all the journal articles used for dose-response modeling to identify, categorize, and quantify dosimetric uncertainties. These uncertainties fell into 6 broad categories. A uniform nomenclature was developed for describing the "dosimetric quality" of the articles used in the PENTEC reviews. Among the multidisciplinary experts in the PENTEC effort, the medical physicists were charged with the dosimetric evaluation, as they are most expert in this subject.

RESULTS

The percentage dosimetric uncertainty was estimated for each late effect endpoint for all PENTEC organ reports. Twelve specific sources of dose uncertainty were identified related to the 6 broad categories. The most common reason for organ dose uncertainty was that prescribed dose rather than organ dose was reported. Percentage dose uncertainties ranged from 5% to 200%. Systematic uncertainties were used to correct the dose component of the models. Random uncertainties were also described in each report and in some cases used to modify dose axis error bars. In addition, the potential effects of dose binning were described.

CONCLUSIONS

PENTEC reports are designed to provide guidance to radiation oncologists and treatment planners for organ dose constraints. It is critical that these dose constraint recommendations are as accurate as possible, acknowledging the large error bars for many. Achieving this accuracy is important as it enables clinicians to better balance target dose coverage with risk of late effects. Evidence-based dose constraints for pediatric patients have been lacking and, in this regard, PENTEC fills an important unmet need. One must be aware of the limitations of our recommendations, and that for some organ systems, large uncertainties exist in the dose-response model because of clinical endpoint uncertainty, dosimetric uncertainty, or both.

Health Benefits and Cost-Effectiveness of Children's Oncology Group Breast Cancer Screening Guidelines for Chest-Irradiated Hodgkin Lymphoma Survivors

PURPOSE

To evaluate the outcomes and cost-effectiveness of the Children's Oncology Group Guideline recommendation for breast cancer (BC) screening using mammography (MAM) and breast magnetic resonance imaging (MRI) in female chest-irradiated childhood Hodgkin lymphoma (HL) survivors. Digital breast tomosynthesis (DBT), increasingly replacing MAM in practice, was also examined.

METHODS

Life years (LYs), quality-adjusted LYs (QALYs), BC mortality, health care costs, and false-positive screen frequencies of undergoing annual MAM, DBT, MRI, MAM + MRI, and DBT + MRI from age 25 to 74 years were estimated by microsimulation. BC risks and non-BC mortality were estimated from female 5-year survivors of HL in the Childhood Cancer Survivor Study and the US population. Test performance of MAM and MRI was synthesized from HL studies, and that of DBT from the general population. Costs (2017 US dollars [USD]) and utility weights were obtained from the medical literature. Incremental cost-effectiveness ratios (ICERs) were calculated.

RESULTS

With 100% screening adherence, annual BC screening extended LYs by 0.34-0.46 years over no screening. If the willingness-to-pay threshold to gain a quality-adjusted LY was ICER < $100,000 USD, annual MAM at age 25-74 years was the only cost-effective strategy. When nonadherence was taken into consideration, only annual MAM at age 30-74 years (ICER = $56,972 USD) was cost-effective. Supplementing annual MAM with MRI costing $545 USD was not cost-effective under either adherence condition. If MRI costs were reduced to $300 USD, adding MRI to annual MAM at age 30-74 years could become more cost-effective, particularly in the reduced adherence condition (ICER = $133,682 USD).

CONCLUSION

Annual BC screening using MAM at age 30-74 years is effective and cost-effective in female chest-irradiated HL survivors. Although annual adjunct MRI is not cost-effective at $545 USD cost, it could become cost-effective as MRI cost is reduced, a plausible scenario with the emergent use of abbreviated MRI.

Deep Learning-Based Dose Prediction for Automated, Individualized Quality Assurance of Head and Neck Radiation Therapy Plans

PURPOSE

This study aimed to use deep learning-based dose prediction to assess head and neck (HN) plan quality and identify suboptimal plans.

METHODS AND MATERIALS

A total of 245 volumetric modulated arc therapy HN plans were created using RapidPlan knowledge-based planning (KBP). A subset of 112 high-quality plans was selected under the supervision of an HN radiation oncologist. We trained a 3D Dense Dilated U-Net architecture to predict 3-dimensional dose distributions using 3-fold cross-validation on 90 plans. Model inputs included computed tomography images, target prescriptions, and contours for targets and organs at risk (OARs). The model's performance was assessed on the remaining 22 test plans. We then tested the application of the dose prediction model for automated review of plan quality. Dose distributions were predicted on 14 clinical plans. The predicted versus clinical OAR dose metrics were compared to flag OARs with suboptimal normal tissue sparing using a 2 Gy dose difference or 3% dose-volume threshold. OAR flags were compared with manual flags by 3 HN radiation oncologists.

RESULTS

The predicted dose distributions were of comparable quality to the KBP plans. The differences between the predicted and KBP-planned D_1%,D_95%, and D_99% across the targets were within -2.53% ± 1.34%, -0.42% ± 1.27%, and -0.12% ± 1.97%, respectively, and the OAR mean and maximum doses were within -0.33 ± 1.40 Gy and -0.96 ± 2.08 Gy, respectively. For the plan quality assessment study, radiation oncologists flagged 47 OARs for possible plan improvement. There was high interphysician variability; 83% of physician-flagged OARs were flagged by only one of 3 physicians. The comparative dose prediction model flagged 63 OARs, including 30 of 47 physician-flagged OARs.

CONCLUSIONS

Deep learning can predict high-quality dose distributions, which can be used as comparative dose distributions for automated, individualized assessment of HN plan quality.

Chronic conditions, late mortality, and health status after childhood AML: a Childhood Cancer Survivor Study report

Five-year survival following childhood acute myeloid leukemia (AML) has increased following improvements in treatment and supportive care. Long-term health outcomes are unknown. To address this, cumulative incidence of late mortality and grades 3 to 5 chronic health condition (CHC) were estimated among 5-year AML survivors diagnosed between 1970 and 1999. Survivors were compared by treatment group (hematopoietic cell transplantation [HCT], chemotherapy with cranial radiation [chemo + CRT], chemotherapy only [chemo-only]), and diagnosis decade. Self-reported health status was compared across treatments, diagnosis decade, and with siblings. Among 856 survivors (median diagnosis age, 7.1 years; median age at last follow-up, 29.4 years), 20-year late mortality cumulative incidence was highest after HCT (13.9%; 95% confidence interval [CI], 10.0%-17.8%; chemo + CRT, 7.6%; 95% CI, 2.2%-13.1%; chemo-only, 5.1%; 95% CI, 2.8%-7.4%). Cumulative incidence of mortality for HCT survivors diagnosed in the 1990s (8.5%; 95% CI, 4.1%-12.8%) was lower vs those diagnosed in the 1970s (38.9%; 95% CI, 16.4%-61.4%). Most survivors did not experience any grade 3 to 5 CHC after 20 years (HCT, 45.8%; chemo + CRT, 23.7%; chemo-only, 27.0%). Furthermore, a temporal reduction in CHC cumulative incidence was seen after HCT (1970s, 76.1%; 1990s, 38.3%; P = .02), mirroring reduced use of total body irradiation. Self-reported health status was good to excellent for 88.2% of survivors; however, this was lower than that for siblings (94.8%; P < .0001). Although HCT is associated with greater long-term morbidity and mortality than chemotherapy-based treatment, gaps have narrowed, and all treatment groups report favorable health status.

Germline Genetic and Treatment-Related Risk Factors for Diabetes Mellitus in Survivors of Childhood Cancer: A Report From the Childhood Cancer Survivor Study and St Jude Lifetime Cohorts

PURPOSE

To characterize germline genetic risk factors of diabetes mellitus among long-term survivors of childhood cancer.

METHODS

Adult survivors of childhood cancer from the Childhood Cancer Survivor Study (CCSS) Original Cohort (n = 5,083; 383 with diabetes) were used to conduct a discovery genome-wide association study. Replication was performed using the CCSS Expansion (n = 2,588; 40 with diabetes) and the St Jude Lifetime (SJLIFE; n = 3,351; 208 with diabetes) cohorts. Risk prediction models, stratified on exposure to abdominal radiation, were calculated using logistic regression including attained age, sex and body mass index, diagnosis, alkylating chemotherapy, age at cancer diagnosis, and a polygenic risk score (PRS) on the basis of 395 diabetes variants from the general population. Area under the receiver operating characteristic curve (AUC) was calculated for models on the basis of traditional risk factors, clinical risk factors, and PRS.

RESULTS

There was a genome-wide significant association of rs55849673-A with diabetes among survivors (odds ratio, 2.9; 95% CI, 2.0 to 4.2; P = 3.7 × 10^-8), which is related to expression of ERCC6L2 in the Genotype-Tissue Expression project. The association of rs55849673-A was observed largely among survivors not exposed to abdominal radiation (odds ratio = 3.5, P = 1.1 × 10^-7) and the frequency of rs55849673-A was consistently higher among diabetic survivors in the CCSS Expansion and SJLIFE cohorts. Risk prediction models including traditional diabetes risk factors, clinical risk factors and PRS had an optimism-corrected AUC of 0.801, with an AUC of 0.751 in survivors treated with abdominal radiation versus 0.813 in survivors who did not receive abdominal radiation.

CONCLUSION

There is evidence for a novel locus of diabetes among survivors not exposed to abdominal radiation. Further refinement and validation of clinic-based risk prediction models for diabetes among long-term survivors of childhood cancer is warranted.

Cohort profile: Risk and risk factors for female breast cancer after treatment for childhood and adolescent cancer: an internationally pooled cohort

PURPOSE

The International Consortium for Pooled Studies on Subsequent Malignancies after Childhood and Adolescent Cancer was established in 2018 to address gaps in knowledge of risk and risk factors for breast cancer subsequent to childhood/adolescent cancer by pooling individual patient data from seven cohorts. Initially, the pooled cohort will focus on three clinically relevant questions regarding treatment-related subsequent breast cancer risk in female survivors, which are the risk related to low-dose radiotherapy exposure to the chest, specific chemotherapy agents and attained age.

PARTICIPANTS

The consortium database includes pooled data on 21 892 female survivors from seven cohorts in North America and Europe with a primary cancer diagnosis at <21 years of age, and survival ≥5 years from diagnosis.

FINDINGS TO DATE

This is a newly established pooled study. The cohort profile summarised the data collected from each included cohort, including childhood cancer diagnosis information and treatment details (ie, radiotherapy fields and cumulative doses, and chemotherapy agents and cumulative doses for each agent). Included cohorts' follow-up started 1951-1981 and ended 2013-2021, respectively, for a median follow-up duration of 24.3 (IQR 18.0-32.8) years since primary cancer diagnosis. The median age at primary cancer diagnosis was 5.4 (IQR 2.5-11.9) years. And the median attained age at last follow-up was 32.2 (IQR 24.0-40.4) years. In all, 4240 (19.4%) survivors were treated with radiotherapy to the chest and 9308 (42.5%) with anthracyclines. At the end of the follow-up, 835 females developed a first subsequent breast cancer, including 635 invasive breast cancer only, 184 carcinomas in situ only (172 ductal carcinomas in situ and 12 lobular carcinomas in situ), and 16 with both an invasive and in situ diagnosis at the same moment. The cumulative incidences of subsequent breast cancer (both invasive and in situ) 25 and 35 years after primary cancer diagnosis were 2.2% and 6.2%, respectively.

FUTURE PLANS

The consortium is intended to serve as a model and robust source of childhood/adolescent cancer survivor data for elucidating other knowledge gaps on subsequent breast cancer risk, and risk of other subsequent malignancies (including data on males) in the future.

Development and validation of a population-based anatomical colorectal model for radiation dosimetry in late effects studies of survivors of childhood cancer

PURPOSE

The purposes of this study were to develop and integrate a colorectal model that incorporates anatomical variations of pediatric patients into the age-scalable MD Anderson Late Effects (MDA-LE) computational phantom, and validate the model for pediatric radiation therapy (RT) dose reconstructions.

METHODS

Colorectal contours were manually derived from whole-body non-contrast computed tomography (CT) scans of 114 pediatric patients (age range: 2.1-21.6 years, 74 males, 40 females). One contour was used for an anatomical template, 103 for training and 10 for testing. Training contours were used to create a colorectal principal component analysis (PCA)-based statistical shape model (SSM) to extract the population's dominant deformations. The SSM was integrated into the MDA-LE phantom. Geometric accuracy was assessed between patient-specific and SSM contours using several overlap metrics. Two alternative colorectal shapes were generated using the first 17 dominant modes of the PCA-based SSM. Dosimetric accuracy was assessed by comparing colorectal doses from test patients' CT-based RT plans (ground truth) with reconstructed doses for the mean and two alternative models in age-matched MDA-LE phantoms.

RESULTS

When using all 103 PCA modes, the mean (min-max) Dice similarity coefficient, distance-to-agreement and Hausdorff distance between the patient-specific and reconstructed contours for the test patients were 0.89 (0.85-0.91), 2.1 mm (1.7-3.0), and 8.6 mm (5.7-14.3), respectively. The average percent difference between reconstructed and ground truth mean and maximum colorectal doses for the mean (alternative 1, 2) model were 6.3% (8.1%, 6.1%) and 4.4% (4.3%, 4.7%), respectively.

CONCLUSIONS

We developed, validated and integrated a colorectal PCA-based SSM into the MDA-LE phantom and demonstrated its dosimetric performance for accurate pediatric RT dose reconstruction.

Association of Changes in Cancer Therapy Over 3 Decades With Risk of Subsequent Breast Cancer Among Female Childhood Cancer Survivors: A Report From the Childhood Cancer Survivor Study (CCSS)

Importance

Breast cancer is the most common invasive subsequent malignant disease in childhood cancer survivors, though limited data exist on changes in breast cancer rates as primary cancer treatments have evolved.

Objective

To quantify the association between temporal changes in cancer treatment over 3 decades and subsequent breast cancer risk.

Design, Setting, and Participants

Retrospective cohort study of 5-year cancer survivors diagnosed when younger than 21 years between 1970 and 1999, with follow-up through December 5, 2020.

Exposures

Radiation and chemotherapy dose changes over time.

Main Outcomes and Measures

Breast cancer cumulative incidence rates and age-specific standardized incidence ratios (SIRs) compared across treatment decades (1970-1999). Piecewise exponential models estimated invasive breast cancer and ductal carcinoma in situ (DCIS) risk and associations with treatment exposures, adjusted for age at childhood cancer diagnosis and attained age.

Results

Among 11 550 female survivors (median age, 34.2 years; range 5.6-66.8 years), 489 developed 583 breast cancers: 427 invasive, 156 DCIS. Cumulative incidence was 8.1% (95% CI, 7.3%-9.0%) by age 45 years. An increased breast cancer risk (SIR, 6.6; 95% CI, 6.1-7.2) was observed for survivors compared with the age-sex-calendar-year-matched general population. Changes in therapy by decade included reduced rates of chest (34% in the 1970s, 22% in the 1980s, and 17% in the 1990s) and pelvic radiotherapy (26%, 17%, and 13% respectively) and increased rates of anthracycline chemotherapy exposures (30%, 51%, and 64%, respectively). Adjusting for age and age at diagnosis, the invasive breast cancer rate decreased 18% every 5 years of primary cancer diagnosis era (rate ratio [RR], 0.82; 95% CI, 0.74-0.90). When accounting for chest radiotherapy exposure, the decline attenuated to an 11% decrease every 5 years (RR, 0.89; 95% CI, 0.81-0.99). When additionally adjusted for anthracycline dose and pelvic radiotherapy, the decline every 5 years increased to 14% (RR, 0.86; 95% CI, 0.77-0.96). Although SIRs of DCIS generally increased over time, there were no statistically significant changes in incidence.

Conclusions and Relevance

Invasive breast cancer rates in childhood cancer survivors have declined with time, especially in those younger than 40 years. This appears largely associated with the reduced use of chest radiation therapy, but was tempered by concurrent changes in other therapies.

LGG-24. Neurocognitive impairment and functional independence in adult survivors of childhood glioma: A report from the Childhood Cancer Survivor Study (CCSS)

PURPOSE: Survivors of pediatric glioma are at risk of developing physical and neurocognitive sequelae secondary to their tumor and its treatment. The contribution of these conditions to attainment of functional independence has not previously been examined. METHODS: 1,284 adult survivors of pediatric glioma (48% male, median [range] 30 [18-51] years at assessment, 22 [15-34] years since diagnosis) completed the CCSS Neurocognitive Questionnaire with impairment defined as scores > 90th %ile of sibling norms. Treatment exposures were categorized as surgery only, chemotherapy (± surgery), or cranial radiation (± chemotherapy/surgery). Self-reported chronic health conditions (CHCs) were graded by organ system using NCI’s CTCAE v4.3. Latent class analysis utilized six factors (employment, marital status, independent living, driver’s license, assistance with routine needs, assistance with personal care needs) to identify classes of functional independence. Multivariable modified Poisson regression evaluated relative risk (RR) of neurocognitive impairment between the classes, adjusting for sex, race, age at assessment, and age at diagnosis. Path analysis explored the impact of treatment exposures on functional independence, mediated by Grade 2-4 CHCs and neurocognitive impairment. RESULTS: Three latent classes of functional independence were identified: independent (58%), moderately independent (20%), and non-independent (22%). Compared to the independent class, non-independent survivors were at elevated risk for impaired task efficiency (RR=3.86, 95% CI, 2.97-5.01), memory (RR=2.39, 95% CI, 1.91-2.98), organization (RR=2.04, 95% CI, 1.64-2.54), and emotional regulation (RR=1.67, 95% CI, 1.30-2.15). Path analysis revealed significant direct paths from cranial radiation (β=0.14), impaired task efficiency (β=0.42), and sensorimotor (β=0.22) and endocrine conditions (β=0.24) to non-independence. Cranial radiation also was indirectly associated with non-independence through impaired task efficiency (β=0.06), and sensorimotor (β=0.06) and endocrine conditions (β=0.10). CONCLUSIONS: Neurocognitive impairment and chronic health conditions partially mediate the association between treatment exposures and attainment of independence in adulthood, identifying potential intervention targets to promote independence in long-term survivors.

Use and correlates of carotid ultrasound in survivors of childhood cancer: A report from the Childhood Cancer Survivor Study

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Background: Survivors of childhood cancer with history of radiation therapy (RT) to the head/neck/chest are at increased risk for stroke. Children’s Oncology Group Guidelines recommend carotid ultrasound (CU) when clinically indicated or 10 years after RT ≥ 40Gy to the neck. Yet, the use of CU has not been previously described. Methods: 8,693 survivors of childhood cancer (median age at diagnosis 8.0 years, range 0-20; median age at evaluation 37.4, range 18-65) diagnosed between 1970-1999 were asked if they had ever had a CU. Cardiovascular disease (CVD) was defined as any of the following: stroke, congestive heart failure, hypertension, myocardial infarction, coronary heart disease, or arrythmia. Prevalence ratios (PR) were calculated; age and sex-adjusted multivariable Poisson regression models evaluated factors associated with CU. Results: 4.9% (427) of survivors had a history of stroke and 28% (2,442) had a history of any CVD. Of these, 40.0% (171) with a history of stroke and 28.6% (748) with any CVD had CU. Comparatively, 14.6% (1,404) without a stroke and 11.1% (798) without any CVD had a CU (both p<0.0001 vs those with condition). Among survivors without CVD, having seen only a primary care physician was not associated with CU (PR 0.84 95% CI 0.58-1.25, p = 0.36), while seeing a cancer specialist (+/- a primary care physician) (PR 1.83 95% CI 1.23-2.79, p = 0.036) was associated with increased likelihood of CU compared to seeing neither. Survivors who had had other surveillance studies, including a colonoscopy (PR 1.76 95% CI 1.44-2.17, p<0.0001), skin cancer exam (PR 1.62 95% CI 1.30-2.03, p=0.0002), or mammogram (PR 2.06 95%CI 1.42-3.07, p<0.0001) were more likely to have a carotid ultrasound, compared to those without that test. Having a history of anthracyclines or RT to the neck were associated with higher prevalence of CU, with RT to the neck exhibiting a dose-response relationship (Table). Conclusions: CU was more common among survivors with a history of stroke or other CVD event. In those without CVD, CU use was associated with anthracyclines and RT dose exposures and with care provided by a cancer specialist. A high proportion (70%) of survivors who received >40Gy RT to the neck have never had a CU, suggesting that greater awareness of guidelines is needed.[Table: see text]

Symptom profiles and health care utilization in long-term survivors of Survivors of Childhood Childhood Cancer Survivor (CCSS) study

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Background: Physical and psychological symptoms co-occur among survivors of childhood cancer, and subgroups with high symptom burden may be at increased risk for problematic healthcare utilization (HCU). Methods: Childhood Cancer Survivor Study participants (N = 17,231; Mean [SD] age = 27.4 [5.98]; 79% non-Hispanic White; 48% female) self-reported sensory, motor, cardiac, respiratory, pain, gastrointestinal, fatigue, memory, depression, and anxiety symptoms at baseline evaluation and latent class analysis identified symptom profiles. Chronic health conditions (CHCs) at baseline (graded per CTCAE 1-2 [mild or moderate; reference] vs 3-4 [severe-life threatening or disabling). HCU (no health care, general care, oncology-focused, long-term follow-up, emergency room visit) for the past 2 years was assessed 6.3 median years after baseline. Logistic regressions examined associations between class membership and follow-up HCU, adjusted for sex, age, health insurance and CHCs. Results: Five symptom classes were identified: 1) Global symptoms (global; 7.7%); 2) emotional distress and pain (distress-pain; 13.3%); 3) neurologic and pain (neuro-pain; 10.6%); 4) cardiopulmonary and pain (cardio-pain; 5.3%); 5) non-elevated symptoms (norm; 63.1%). Bone tumor survivors had higher risk of falling into global, neuro-pain and cardio-pain groups (p’s < .001), and CNS tumor survivors had higher risk of falling into global and neuro-pain group (all p < .001) compared to leukemia survivors. Radiation, Grade 3-4 CHCs, female sex, and older age increased risk of global, distress-pain, neuro-pain and cardio-pain membership compared to norm (all p’s < .001). Oncology-focused care was more common in cardio-pain and global symptom groups, while long-term follow-up care was more common in neuro-pain and global groups (Table). All elevated symptoms groups were more likely to have emergency room visits compared to norm group. Conclusions: Adjusting for insurance, CHCs and older age, elevated symptoms are associated with future emergency room use. Pain is prevalent in all high symptom groups, and suggests an important intervention target.[Table: see text]

Modifiable risk factors for late mortality among five-year survivors of childhood cancer: A report from the Childhood Cancer Survivor Study

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Background: The impact ofmodifiable lifestyle and cardiovascular risk factors (CVRFs) on risk for late mortality in adult survivors of childhood cancer is not well established. Methods: All-cause and health-related late (>5 years from cancer diagnosis) mortality (HRM; excludes death from primary cancer and external causes) were evaluated in five-year survivors diagnosed <21 years of age using the National Death Index through 2017. Modifiable lifestyle (smoking status, alcohol use, physical activity, body mass index [BMI]; combined to create a score [0-4] and categorized as unhealthy [0-2], moderate [2.5 or 3], healthy [3.5 or 4]) and CVRFs (hypertension [HTN], diabetes [DM], dyslipidemia) were assessed as time-varying covariates. Standardized mortality ratios (SMRs) and absolute excess risk of death per 1000 person-years (AER) with 95% confidence intervals (CIs) were estimated. Multivariable models estimated the relative risk (RR) of death adjusted for demographic and socioeconomic variables. Results: Among 20,051 adult survivors (median age 40.0 years, range 18.7 – 67.7), 19% reported ≥1 CVRF (13% HTN, 9% dyslipidemia, 5% DM) and few reported a healthy lifestyle (29% healthy, 40% moderate, 31% unhealthy). There were 1476 deaths due to health-related causes. While all survivors experienced an increased risk of HRM compared to the US population, risk was lower among those with a healthy vs. unhealthy lifestyle (SMR 3.5, 95% CI 3.1-3.9 vs. 6.2, 5.7-6.7) and very high among underweight survivors (11.1, 9.3-13.3) and those with both HTN and DM (13.0, 9.2-18.0). Stratified by lifestyle score, the excess risk of HRM was lowest in those with a healthy lifestyle across survival time (Table). Similar trends were seen when stratified by 0, 1 and 2 CVRFs. In multivariable models, compared to survivors with no CVRFs and healthy lifestyle, no CVRFs and unhealthy lifestyle was associated with a 50% increased risk of HRM (RR 1.5, 95% CI 1.2-1.8) and unhealthy lifestyle plus HTN a 2-fold increased risk of HRM (2.2, 1.6-2.8). Regardless of lifestyle group, ≥2 CVRF increased risk for HRM at least 2-fold (p-values <0.001). Conclusions: A reduction in excess deaths is observed among adult survivors of childhood cancer with a healthy lifestyle and no CVRFs as they age. Interventions that target improved lifestyle choices and prevention or aggressive treatment of modifiable CVRFs may reduce risk for late mortality. [Table: see text]

Joint effects of general population polygenic risk scores (PRS) and radiation treatment on subsequent neoplasm risk among childhood cancer survivors: A report from the Childhood Cancer Survivor Study (CCSS)

10008

Background: We examined whether PRS from general population studies are associated with risk of subsequent neoplasms (SNs) in childhood cancer survivors and evaluated joint associations between PRS and radiation treatment (RT), an established SN risk factor. Methods: Common genetic variants associated with risk of basal cell carcinoma (BCC), breast cancer, thyroid cancer, squamous cell carcinoma (SCC) or melanoma in general population studies were used to calculate cancer specific PRS among 5,911 5 year cancer survivors diagnosed < 21 years of age and between 1970-1986 in the CCSS. We examined associations between each PRS and SN risk using conditional logistic regression in nested case control studies, with incidence density sampling and matching on childhood cancer type, age at diagnosis, sex, RT dose to the SN site, and chemotherapy exposure. Further analyses matching only on non-treatment factors assessed joint associations considering potential combinations of PRS and RT exposure. We calculated the relative excess risk due to interaction (RERI) to determine whether joint associations were consistent with additivity of the individual risk factors (RERI > 0 indicates a more-than-additive joint association). Results: Among survivors (median age at follow-up 40 years, range 3-67; 62% exposed to RT), cancer specific PRS were associated with risk of subsequent BCC (N = 626; quartile 4 versus 1, OR [95% CI] = 1.9 [1.5-2.4]), breast cancer (N = 277; 4.5 [2.8-7.1]), thyroid cancer (N = 149; 1.9 [1.2-3.1]), and melanoma (N = 76; 2.7 [1.3-5.6]). Both PRS and RT were independently associated with SN risk, but joint analyses using a common reference group (PRS < median, RT < 1 Gy) found that both risk factors together resulted in more-than-additive increases in risk of BCC (RERI [95% CI] = 6.9 [2.0-11.8], breast cancer (6.6 [2.2-10.1], and thyroid cancer (4.8 [0.5-9.2]). Specifically, BCC risk was increased 28.8-fold for both PRS ≥ median and RT ≥ 1 Gy together, but only 3.3-fold for PRS ≥ median alone and 19.7-fold for RT ≥ 1 Gy alone. Similarly, breast cancer risk was increased 14.1-fold for both risk factors together, 2.5-fold for PRS ≥ median alone, and 6.5-fold for RT ≥ 1 Gy alone, and thyroid cancer risk was increased 12.3-fold for both risk factors together, 2.4-fold for PRS ≥ median alone, and 6.0-fold for RT ≥ 1 Gy alone. In joint analyses using more detailed RT categories, we found more-than-additive joint associations at both low and high RT doses. Conclusions: General population PRS were associated with SN risks after childhood cancer. More-than-additive increased risks with the combination of PRS and RT suggest that established markers of genetic susceptibility remain important in the context of treatment-related risks and may be useful in further refining risk assessment and follow-up guidelines for survivors.

Late mortality and morbidity among adult survivors of childhood glioma treated over three decades: A report from the Childhood Cancer Survivor Study

10007

Background: Therapy for pediatric low-grade glioma has evolved to delay or eliminate the need for cranial radiation. The impact of this change in approach on long-term outcomes remains unknown. Methods: Cumulative incidence of late mortality (death ≥5 years from diagnosis), subsequent neoplasms (SNs), and chronic health conditions (CHCs, graded using CTCAE criteria) were evaluated in the Childhood Cancer Survivor Study among 5-year survivors of glioma diagnosed between 1970 and 1999. Outcomes were evaluated by diagnosis decade (1970s, 1980s, 1990s) and by treatment exposure in the first five years from diagnosis [surgery only, chemotherapy (with or without surgery), and cranial radiation (with or without surgery or chemotherapy)]. Relative Risk (RRs) with 95% CIs estimated long-term outcomes using multivariable piecewise exponential models. Results: Among 2,684 eligible survivors (median age at diagnosis, 7 years [range, 0 to 20 years]; median time from diagnosis, 24 years [range, 5 to 48 years]), the proportion exposed to cranial radiation decreased from 51% (1970s) to 45% (1980s) and 25% (1990s) while the rate of recurrence within > 5 years but ≤15 years of diagnosis decreased from 9.8% (1970s) to 8.8% (1980s) and 5.0% (1990s). The 15-year cumulative incidence rate of all-cause late mortality was 10.3% (1970s), 6.5% (1980s), and 6.0% (1990s) (p < 0.001, comparison of cumulative incidence curves). The 15-year cumulative incidence rates of severe, disabling or life-threatening (grade 3-5) CHCs also decreased between 1970 and 1999: 19.7% (1970s), 17.8% (1980s), and 14.2% (1990s) (p < 0.0001). Lower rates of SN were not observed. In a multivariable analysis adjusted for age at diagnosis, attained age, race, sex and diagnosis decade, later diagnosis (1990s vs. 1970s) was associated with lower risk of late mortality (RR 0.86, 95% CI 0.74-0.99), grade 3-5 CHCs (RR 0.65, 95% CI 0.51-0.82) and SN (RR 0.64, 95% CI 0.44-0.94). In addition, when treatment exposure was added to the multivariable model, the effect of diagnosis decade was attenuated and no longer significant. Exposure to radiation or chemotherapy both increased risk compared to surgery alone: all-cause mortality (radiation RR 4.95, 95% CI 3.79-6.47; chemotherapy RR 2.88, 95% CI 1.85-4.48), grade 3-5 CHCs (radiation RR 4.02, 95% CI 3.28-4.94; chemotherapy RR 1.66, 95% CI 1.13-2.45), SNs (radiation RR 4.02, 95% CI 3.06-6.13, chemotherapy RR 2.08, 95% CI 1.03-4.23)). The effect of delayed radiation (> 1year to ≤5 years from diagnosis) on all-cause late mortality, grade 3-5 CHCs, or SNs was not different compared to radiation within one year of diagnosis. Conclusions: Late mortality and CHCs decreased in childhood glioma survivors diagnosed from 1970-1999 largely due to therapy changes, particularly avoidance of cranial radiation, without increased late recurrence.

Primary hypothyroidism in childhood cancer survivors: Prevalence, risk factors, and long-term consequences

BACKGROUND

Data on primary hypothyroidism and its long-term impact on the health, cognition, and quality of life (QOL) of childhood cancer survivors are limited. This study examined the prevalence of and risk factors for primary hypothyroidism and its associations with physical, neurocognitive, and psychosocial outcomes.

METHODS

This was a retrospective study with a cross-sectional health outcome analysis of an established cohort comprising 2965 survivors of childhood cancer (52.8% male; median current age, 30.9 years, median time since cancer diagnosis, 22.3 years). Multivariable logistic regression estimated odds ratios (ORs) and 95% confidence intervals (CIs) for associations between primary hypothyroidism and cancer-related risk factors, cardiovascular disease risk factors, frailty, neurocognitive and QOL outcomes, social attainment, and subsequent thyroid carcinoma. Associations between serum free thyroxine and thyrotropin levels at assessment and health outcomes were explored.

RESULTS

The prevalence of primary hypothyroidism was 14.7% (95% CI, 13.5%-16.0%). It was more likely in females (OR, 1.06; 95% CI, 1.03-1.08), was less likely in non-Whites (OR, 0.96; 95% CI, 0.93-0.99), was associated with thyroid radiotherapy (higher risk at higher doses), and was more common if cancer was diagnosed at an age ≥ 15.0 years versus an age < 5 years (OR, 1.05; 95% CI, 1.01-1.09). Primary hypothyroidism was associated with frailty (OR, 1.54; 95% CI, 1.05-2.26), dyslipidemia (OR, 1.52; 95% CI, 1.14-2.04), impaired physical QOL (OR, 1.66; 95% CI, 1.12-2.48), and having health care insurance (OR, 1.51; 95% CI, 1.07-2.12).

CONCLUSIONS

Primary hypothyroidism is common in survivors and is associated with unfavorable physical health and QOL outcomes. The impact of thyroid hormone replacement practices on these outcomes should be investigated further.

Body region-specific 3D age-scaling functions for scaling whole-body computed tomography anatomy for pediatric late effects studies

Purpose.Radiation epidemiology studies of childhood cancer survivors treated in the pre-computed tomography (CT) era reconstruct the patients' treatment fields on computational phantoms. For such studies, the phantoms are commonly scaled to age at the time of radiotherapy treatment because age is the generally available anthropometric parameter. Several reference size phantoms are used in such studies, but reference size phantoms are only available at discrete ages (e.g.: newborn, 1, 5, 10, 15, and Adult). When such phantoms are used for RT dose reconstructions, the nearest discrete-aged phantom is selected to represent a survivor of a specific age. In this work, we (1) conducted a feasibility study to scale reference size phantoms at discrete ages to various other ages, and (2) evaluated the dosimetric impact of using exact age-scaled phantoms as opposed to nearest age-matched phantoms at discrete ages.Methods.We have adopted the University of Florida/National Cancer Institute (UF/NCI) computational phantom library for our studies. For the feasibility study, eight male and female reference size UF/NCI phantoms (5, 10, 15, and 35 years) were downscaled to fourteen different ages which included next nearest available lower discrete ages (1, 5, 10 and 15 years) and the median ages at the time of RT for Wilms' tumor (3.9 years), craniospinal (8.0 years), and all survivors (9.1 years old) in the Childhood Cancer Survivor Study (CCSS) expansion cohort treated with RT. The downscaling was performed using our in-house age scaling functions (ASFs). To geometrically validate the scaling, Dice similarity coefficient (DSC), mean distance to agreement (MDA), and Euclidean distance (ED) were calculated between the scaled and ground-truth discrete-aged phantom (unscaled UF/NCI) for whole-body, brain, heart, liver, pancreas, and kidneys. Additionally, heights of the scaled phantoms were compared with ground-truth phantoms' height, and the Centers for Disease Control and Prevention (CDC) reported 50th percentile height. Scaled organ masses were compared with ground-truth organ masses. For the dosimetric assessment, one reference size phantom and seventeen body-size dependent 5-year-old phantoms (9 male and 8 female) of varying body mass indices (BMI) were downscaled to 3.9-year-old dimensions for two different radiation dose studies. For the first study, we simulated a 6 MV photon right-sided flank field RT plan on a reference size 5-year-old and 3.9-year-old (both of healthy BMI), keeping the field size the same in both cases. Percent of volume receiving dose ≥15 Gy (V₁₅) and the mean dose were calculated for the pancreas, liver, and stomach. For the second study, the same treatment plan, but with patient anatomy-dependent field sizes, was simulated on seventeen body-size dependent 5- and 3.9-year-old phantoms with varying BMIs. V₁₅, mean dose, and minimum dose received by 1% of the volume (D₁), and by 95% of the volume (D₉₅) were calculated for pancreas, liver, stomach, left kidney (contralateral), right kidney, right and left colons, gallbladder, thoracic vertebrae, and lumbar vertebrae. A non-parametric Wilcoxon rank-sum test was performed to determine if the dose to organs of exact age-scaled and nearest age-matched phantoms were significantly different (p < 0.05).Results.In the feasibility study, the best DSCs were obtained for the brain (median: 0.86) and whole-body (median: 0.91) while kidneys (median: 0.58) and pancreas (median: 0.32) showed poorer agreement. In the case of MDA and ED, whole-body, brain, and kidneys showed tighter distribution and lower median values as compared to other organs. For height comparison, the overall agreement was within 2.8% (3.9 cm) and 3.0% (3.2 cm) of ground-truth UF/NCI and CDC reported 50th percentile heights, respectively. For mass comparison, the maximum percent and absolute differences between the scaled and ground-truth organ masses were within 31.3% (29.8 g) and 211.8 g (16.4%), respectively (across all ages). In the first dosimetric study, absolute difference up to 6% and 1.3 Gy was found for V₁₅and mean dose, respectively. In the second dosimetric study, V₁₅and mean dose were significantly different (p < 0.05) for all studied organs except the fully in-beam organs. D₁and D₉₅were not significantly different for most organs (p > 0.05).Conclusion.We have successfully evaluated our ASFs by scaling UF/NCI computational phantoms from one age to another age, which demonstrates the feasibility of scaling any CT-based anatomy. We have found that dose to organs of exact age-scaled and nearest aged-matched phantoms are significantly different (p < 0.05) which indicates that using the exact age-scaled phantoms for retrospective dosimetric studies is a better approach.

Subsequent malignant neoplasms in the Childhood Cancer Survivor Study: Occurrence of cancer types in which human papillomavirus is an established etiologic risk factor

BACKGROUND

Human papillomavirus (HPV)-associated subsequent malignant neoplasms (SMN_HPV ) in childhood cancer survivors are poorly understood.

METHODS

The cumulative risk of SMN_HPV was assessed among 24,363 Childhood Cancer Survivor Study participants. Standardized incidence ratios (SIRs) and absolute excess risk were calculated using age-matched, sex-matched, and calendar year rates from the Surveillance, Epidemiology, and End Results program. Poisson regression models identified SMN_HPV risk factors, evaluating relative SIRs (rSIR) and 95% confidence intervals (95% CIs).

RESULTS

In total, 46 survivors developed an SMN_HPV (median age, 31 years [range, 10-56 years]; median time from primary cancer, 21 years [range, 9-35 years]). SMN_HPV sites included oropharynx (N = 44), anorectum (N = 6), uterine cervix (N = 2), and vulva (N = 2). The 33-year cumulative incidence was 0.3% (95% CI, 0.2%-0.4%), and the SIR was nearly 3-fold that of the general population (SIR, 2.86; 95% CI, 2.05-4.00). Female survivors were not at increased risk of cervical or vulvar cancers compared with the general population. All survivors had an elevated risk of oropharyngeal SMN_HPV (males: SIR, 4.06; 95% CI, 2.37-6.97; females: SIR, 8.44; 95% CI 4.88-14.61) and anorectal SMN_HPV (males: SIR, 13.56; 95% CI, 5.09-36.13; females: SIR, 9.15; 95% CI, 2.29-36.61). Males (vs females: rSIR, 1.99; 95% CI, 1.00-3.94); head, neck, and pelvic radiotherapy doses >3000 centigray (vs none: rSIR, 2.35; 95% CI, 1.11-4.97); and cisplatin-equivalent doses >400 mg/m² (vs none: rSIR, 4.51; 95% CI, 1.78-11.43) were associated with increased SMN_HPV SIRs in multivariable analysis.

CONCLUSIONS

Childhood cancer survivors are at increased risk for SMN in sites susceptible to HPV-associated malignancies. Further research examining HPV in the etiology of SMN and the promotion of HPV vaccination and surveillance guidelines for SMN_HPV in cancer survivors is warranted.

The radiotherapy quality assurance gap among phase III cancer clinical trials

PURPOSE

Quality assurance (QA) practices improve the quality level of oncology trials by ensuring that the protocol is followed and the results are valid and reproducible. This study investigated the utilization of QA among randomized controlled trials that involve radiotherapy (RT).

METHODS AND MATERIALS

We searched ClinicalTrials.gov in February 2020 for all phase III oncology randomized clinical trials (RCTs). These trials were screened for RT-specific RCTs that had published primary trial results. Information regarding QA in each trial was collected from the study publications and trial protocol if available. Two individuals independently performed trial screening and data collection. Pearson's Chi-square tests analyses were used to assess factors that were associated with QA inclusion in RT trials.

RESULTS

Forty-two RCTs with RT as the primary intervention or as a mandatory component of the protocol were analyzed; the earliest was started in 1994 and one trial was still active though not recruiting. Twenty-nine (69%) trials mandated RT quality assurance (RTQA) practices as part of the trial protocol, with 19 (45%) trials requiring institutional credentialing. Twenty-one (50%) trials published protocol deviation outcomes. Clinical trials involving advanced radiation techniques (IMRT, VMAT, SRS, SBRT) did not include more RTQA than trials without these advanced techniques (73% vs. 65%, p = 0.55). Trials that reported protocol deviation outcomes were associated with mandating RTQA in their protocols as compared to trials that did not report these outcomes (100% vs. 38%, p < 0.001).

CONCLUSIONS

There is a lack of RTQA utilization and transparency in RT clinical trials. It is imperative for RT trials to include increased QA for safe, consistent, and high-quality RT planning and delivery.

Lung Cancer as a Subsequent Malignant Neoplasm in Survivors of Childhood Cancer

BACKGROUND

Lung cancer, the most common cause of cancer-related death in adults, has not been well studied as a subsequent malignant neoplasm (SMN) in childhood cancer survivors. We assessed prevalence, risk factors, and outcomes for lung SMN in the Childhood Cancer Survivor Study (CCSS) cohort.

METHODS

Among 25,654 5-year survivors diagnosed with childhood cancer (<21 years), lung cancer was self-reported and confirmed by pathology record review. Standardized incidence ratios (SIR) and cumulative incidences were calculated, comparing survivors to the general population, and hazard ratios (HR) were estimated using Cox regression for diagnosis and treatment exposures.

RESULTS

Forty-two survivors developed a lung SMN [SIR, 4.0; 95% confidence interval (CI), 2.9-5.4] with a cumulative incidence of 0.16% at 30 years from diagnosis (95% CI, 0.09%-0.23%). In a treatment model, chest radiation doses of 10-30 Gy (HR, 3.4; 95% CI, 1.05-11.0), >30-40 Gy (HR, 4.6; 95% CI, 1.5-14.3), and >40 Gy (HR, 9.1; 95% CI, 3.1-27.0) were associated with lung SMN, with a monotone dose trend (P trend < 0.001). Survivors of Hodgkin lymphoma (SIR, 9.3; 95% CI, 6.2-13.4) and bone cancer (SIR, 4.4; 95% CI, 1.8-9.1) were at greatest risk for lung SMN.

CONCLUSIONS

Survivors of childhood cancer are at increased risk for lung cancer compared with the general population. Greatest risk was observed among survivors who received chest radiotherapy or with primary diagnoses of Hodgkin lymphoma or bone cancer.

IMPACT

This study describes the largest number of observed lung cancers in childhood cancer survivors and elucidates need for further study in this aging and growing population.

Photon beam modeling variations predict errors in IMRT dosimetry audits

Background & purpose:

To evaluate treatment planning system (TPS) beam modeling parameters as contributing factors to IMRT audit performance.

Materials & methods:

We retrospectively analyzed IROC Houston phantom audit performance and concurrent beam modeling survey responses from 337 irradiations performed between August 2017 and November 2019. Irradiation results were grouped based on the reporting of typical or atypical beam modeling parameter survey responses (<10th or >90th percentile values), and compared for passing versus failing (>7% error) or “poor” (>5% error) irradiation status. Additionally, we assessed the impact on the planned dose distribution from variations in modeling parameter value. Finally, we estimated the overall impact of beam modeling parameter variance on dose calculations, based on reported community variations.

Results:

Use of atypical modeling parameters were more frequently seen with failing phantom audit results (p = 0.01). Most pronounced was for Eclipse AAA users, where phantom irradiations with atypical values of dosimetric leaf gap (DLG) showed a greater incidence of both poor-performing (p = 0.048) and failing phantom audits (p = 0.014); and in general, DLG value was correlated with dose calculation accuracy (r = 0.397, p < 0.001). Manipulating TPS parameters induced systematic changes in planned dose distributions which were consistent with prior observations of how failures manifest. Dose change estimations based on these dose calculations agreed well with true dosimetric errors identified.

Conclusion:

Atypical TPS beam modeling parameters are associated with failing phantom audits. This is identified as an important factor contributing to the observed failing phantom results, and highlights the need for accurate beam modeling.

Impact of Risk-Stratified Therapy on Health Status in Survivors of Childhood Acute Lymphoblastic Leukemia: A Report from the Childhood Cancer Survivor Study

BACKGROUND

Prior studies have identified that survivors of childhood acute lymphoblastic leukemia (ALL) report poor health status. It is unknown how risk-stratified therapy impacts the health status of ALL survivors.

METHODS

We estimated and compared the prevalence of self-reported poor health status among adult (≥18 years) survivors of childhood ALL diagnosed at age <21 years from 1970 to 1999 and sibling controls, excluding proxy reports. Therapy combinations defined treatment groups representative of 1970s therapy (70s), standard- and high-risk 1980s and 1990s therapy (80sSR, 80sHR, 90sSR, 90sHR), and relapse/bone marrow transplant (R/BMT). Log-binomial models, adjusted for clinical and demographic factors, compared outcomes between groups using prevalence ratios (PR) with 95% confidence intervals (CI).

RESULTS

Among 5,119 survivors and 4,693 siblings, survivors were more likely to report poor health status in each domain including poor general health (13.5% vs. 7.4%; PR = 1.92; 95% CI, 1.69-2.19). Compared with 70s, 90sSR and 90sHR were less likely to report poor general health (90sSR: PR = 0.75; 95% CI, 0.57-0.98; 90sHR: PR = 0.58; 95% CI, 0.39-0.87), functional impairment (90sSR: PR = 0.56; 95% CI, 0.42-0.76; 90sHR: PR = 0.63; 95% CI, 0.42-0.95), and activity limitations (90sSR: 0.61; 95% CI, 0.45-0.83; 90sHR: PR = 0.59; 95% CI, 0.38-0.91). An added adjustment for chronic conditions in multivariable models partially attenuated 90sSR risk estimates.

CONCLUSIONS

Risk-stratified ALL therapy has succeeded in reducing risk for poor general health, functional impairment, and activity limitations among more recent survivors of standard- and high-risk therapy.

IMPACT

Future research into the relationship between risk-stratified therapy, health status, and late health outcomes may provide new opportunities to further improve late morbidity among survivors.

Functional Outcomes and Social Attainment in Asian/Pacific Islander Childhood Cancer Survivors in the United States: A Report from the Childhood Cancer Survivor Study

BACKGROUND

Given the relatively small population of Asians or Pacific Islanders (API) in the United States, studies describing long-term outcomes in API survivors of childhood cancer are limited. This study compared functional outcomes between API versus non-Hispanic White (NHW) survivors.

METHODS

This study included 203 API 5-year survivors [age at follow-up: 29.2 (SD = 6.3) years] and 12,186 NHW survivors [age at follow-up 31.5 (SD = 7.3) years] from the Childhood Cancer Survivor Study. Self-reported functional outcomes of neurocognitive function, emotional distress, quality of life, and social attainment were compared between the two groups using multivariable regression, adjusted for sex, age at diagnosis and evaluation, cancer diagnosis, and neurotoxic treatment.

RESULTS

No statistically significant race/ethnicity-based differences were identified in neurocognitive and emotional measures. API survivors reported, on average, less bodily pain than NHW survivors [mean 54.11 (SD = 8.98) vs. 51.32 (SD = 10.12); P < 0.001]. NHW survivors were less likely to have attained at least a college degree than API survivors [OR = 0.50; 95% confidence interval (CI) = 0.34-0.73]. API survivors were more likely than NHW survivors to be never-married (OR = 2.83; 95% CI = 1.93-4.13) and to live dependently (OR = 3.10; 95% CI = 2.02-4.74). Older age (>45 years), brain tumor diagnosis, and higher cranial radiation dose were associated with poorer functional outcomes in API survivors (all, P < 0.05).

CONCLUSIONS

We observed differences in social attainment between API and NHW survivors, although statistically significant differences in neurocognitive and emotional outcomes were not identified.

IMPACT

Future studies should evaluate whether racial/ethnic differences in environmental and sociocultural factors may have differential effects on health and functional outcomes.

Breast Hypoplasia and Decreased Lactation From Radiation Therapy in Survivors of Pediatric Malignancy: A PENTEC Comprehensive Review

PURPOSE

Breast hypoplasia and impaired lactation are poorly studied sequelae of chest radiation therapy (RT) in children. The Pediatric Normal Tissue Effects in the Clinic female breast task force aimed to quantitate the radiation dose-volume effects on these endpoints.

METHODS AND MATERIALS

A literature search was conducted of peer-reviewed manuscripts evaluating breast hypoplasia and lactation after chest RT in children, yielding 789 abstracts. Only 2 studies on children irradiated at <4 years of age for angioma of the breast provided dosimetric data correlated with breast hypoplasia. For patients who received brachytherapy, the dose was converted to external beam RT in equivalent 2 Gy fractions (DEBRT), although the limitations of this type of mathematical conversion need to be recognized. We calculated relative risks (RR) and 95% confidence intervals (95% CIs) based on these data. Only 1 study was relevant to the lactation endpoint, in which patients were given RT for Hodgkin lymphoma at age 14 to 40 years.

RESULTS

The 3 studies involved 206 patients in total. In patients <4 years old at the time of RT, the prevalence of patient-perceived breast hypoplasia was 38% (RR 2.5; 95% CI, 1.3-4.6) after DEBRT of <0.34 Gy, 61% (RR 4.0; 95% CI, 2.1-7.4) after DEBRT 0.34-0.97 Gy, and 97% (RR 6.3; 95% CI, 3.6-10.8) after DEBRT ≥0.97 Gy to the breast anlage. A simple linear regression model (r = 0.72; P < .001) showed that the treated breast was smaller than the untreated breast by 13% at DEBRT = 0.5 Gy, 20% at DEBRT = 1 Gy, 32% at DEBRT = 2 Gy, 51% at DEBRT = 4 Gy, 66% at DEBRT = 6 Gy, 79% at DEBRT = 8 Gy, and 90% at DEBRT = 10 Gy. The risk of unsuccessful breastfeeding was 39% after a median mediastinal dose of 41 Gy, compared with 21% in a sibling control group (P = .04). RT dose of ≥42 Gy was not associated with less breastfeeding success compared with <42 Gy, and data on lower doses were unavailable.

CONCLUSIONS

Based on extremely limited data, young adults exposed to thoracic RT as children seem to be at significant risk of breast hypoplasia and impaired lactation. Doses as low as 0.3 Gy to immature breasts can cause breast hypoplasia. Additional studies are needed to quantify dose and technique effects with modern RT indications. Prospective collection of clinical outcomes and dosimetric factors would enhance our understanding of RT-induced breast hypoplasia and impaired lactation.