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

PURPOSE

Kidney injury is a known late and potentially devastating complication of abdominal radiation therapy (RT) in pediatric patients. A comprehensive Pediatric Normal Tissue Effects in the Clinic review by the Genitourinary (GU) Task Force aimed to describe RT dose-volume relationships for GU dysfunction, including kidney, bladder, and hypertension, for pediatric malignancies. The effect of chemotherapy was also considered.

METHODS AND MATERIALS

We conducted a comprehensive PubMed search of peer-reviewed manuscripts published from 1990 to 2017 for investigations on RT-associated GU toxicities in children treated for cancer. We retrieved 3271 articles with 100 fulfilling criteria for full review, 24 with RT dose data and 13 adequate for modeling. Endpoints were heterogenous and grouped according to National Kidney Foundation: grade ≥1, grade ≥2, and grade ≥3. We modeled whole kidney exposure from total body irradiation (TBI) for hematopoietic stem cell transplant and whole abdominal irradiation (WAI) for patients with Wilms tumor. Partial kidney tolerance was modeled from a single publication from 2021 after the comprehensive review revealed no usable partial kidney data. Inadequate data existed for analysis of bladder RT-associated toxicities.

RESULTS

The 13 reports with long-term GU outcomes suitable for modeling included 4 on WAI for Wilms tumor, 8 on TBI, and 1 for partial renal RT exposure. These reports evaluated a total of 1191 pediatric patients, including: WAI 86, TBI 666, and 439 partial kidney. The age range at the time of RT was 1 month to 18 years with medians of 2 to 11 years in the various reports. In our whole kidney analysis we were unable to include chemotherapy because of the heterogeneity of regimens and paucity of data. Age-specific toxicity data were also unavailable. Wilms studies occurred from 1968 to 2011 with mean follow-ups 8 to 15 years. TBI studies occurred from 1969 to 2004 with mean follow-ups of 4 months to 16 years. We modeled risk of dysfunction by RT dose and grade of toxicity. Normal tissue complication rates ≥5%, expressed as equivalent doses, 2 Gy/fx for whole kidney exposures occurred at 8.5, 10.2, and 14.5 Gy for National Kidney Foundation grades ≥1, ≥2, and ≥3, respectively. Conventional Wilms WAI of 10.5 Gy in 6 fx had risks of ≥grade 2 toxicity 4% and ≥grade 3 toxicity 1%. For fractionated 12 Gy TBI, those risks were 8% and <3%, respectively. Data did not support whole kidney modeling with chemotherapy. Partial kidney modeling from 439 survivors who received RT (median age, 7.3 years) demonstrated 5 or 10 Gy to 100% kidney gave a <5% risk of grades 3 to 5 toxicity with 1500 mg/m2 carboplatin or no chemo. With 480 mg/m2 cisplatin, a 3% risk of ≥grade 3 toxicity occurred without RT and a 5% risk when 26% kidney received ≥10 Gy. With 63 g/m2 of ifosfamide, a 5% risk of ≥grade 3 toxicity occurred with no RT, and a 10% toxicity risk occurred when 42% kidney received ≥10 Gy.

CONCLUSIONS

In patients with Wilms tumor, the risk of toxicity from 10.5 Gy of WAI is low. For 12 Gy fractionated TBI with various mixtures of chemotherapy, the risk of severe toxicity is low, but low-grade toxicity is not uncommon. Partial kidney data are limited and toxicity is associated heavily with the use of nephrotoxic chemotherapeutic agents. Our efforts demonstrate the need for improved data gathering, systematic follow-up, and reporting in future clinical studies. Current radiation dose used for Wilms tumor and TBI appear to be safe; however, efforts in effective kidney-sparing TBI and WAI regimens may reduce the risks of renal injury without compromising cure.

Partial Breast Irradiation for Patients With Early-Stage Invasive Breast Cancer or Ductal Carcinoma In Situ: An ASTRO Clinical Practice Guideline

PURPOSE

This guideline provides evidence-based recommendations on appropriate indications and techniques for partial breast irradiation (PBI) for patients with early-stage invasive breast cancer and ductal carcinoma in situ.

METHODS

ASTRO convened a task force to address 4 key questions focused on the appropriate indications and techniques for PBI as an alternative to whole breast irradiation (WBI) to result in similar rates of ipsilateral breast recurrence (IBR) and toxicity outcomes. Also addressed were aspects related to the technical delivery of PBI, including dose-fractionation regimens, target volumes, and treatment parameters for different PBI techniques. The guideline is based on a systematic review provided by the Agency for Healthcare Research and Quality. Recommendations were created using a predefined consensus-building methodology and system for grading evidence quality and recommendation strength.

RESULTS

PBI delivered using 3-dimensional conformal radiation therapy, intensity modulated radiation therapy, multicatheter brachytherapy, and single-entry brachytherapy results in similar IBR as WBI with long-term follow-up. Some patient characteristics and tumor features were underrepresented in the randomized controlled trials, making it difficult to fully define IBR risks for patients with these features. Appropriate dose-fractionation regimens, target volume delineation, and treatment planning parameters for delivery of PBI are outlined. Intraoperative radiation therapy alone is associated with a higher IBR rate compared with WBI. A daily or every-other-day external beam PBI regimen is preferred over twice-daily regimens due to late toxicity concerns.

CONCLUSIONS

Based on published data, the ASTRO task force has proposed recommendations to inform best clinical practices on the use of PBI.

The Pediatric Proton and Photon Therapy Comparison Cohort: Study Design for a Multicenter Retrospective Cohort to Investigate Subsequent Cancers After Pediatric Radiation Therapy

Purpose

The physical properties of protons lower doses to surrounding normal tissues compared with photons, potentially reducing acute and long-term adverse effects, including subsequent cancers. The magnitude of benefit is uncertain, however, and currently based largely on modeling studies. Despite the paucity of directly comparative data, the number of proton centers and patients are expanding exponentially. Direct studies of the potential risks and benefits are needed in children, who have the highest risk of radiation-related subsequent cancers. The Pediatric Proton and Photon Therapy Comparison Cohort aims to meet this need.

Methods and Materials

We are developing a record-linkage cohort of 10,000 proton and 10,000 photon therapy patients treated from 2007 to 2022 in the United States and Canada for pediatric central nervous system tumors, sarcomas, Hodgkin lymphoma, or neuroblastoma, the pediatric tumors most frequently treated with protons. Exposure assessment will be based on state-of-the-art dosimetry facilitated by collection of electronic radiation records for all eligible patients. Subsequent cancers and mortality will be ascertained by linkage to state and provincial cancer registries in the United States and Canada, respectively. The primary analysis will examine subsequent cancer risk after proton therapy compared with photon therapy, adjusting for potential confounders and accounting for competing risks.

Results

For the primary aim comparing overall subsequent cancer rates between proton and photon therapy, we estimated that with 10,000 patients in each treatment group there would be 80% power to detect a relative risk of 0.8 assuming a cumulative incidence of subsequent cancers of 2.5% by 15 years after diagnosis. To date, 9 institutions have joined the cohort and initiated data collection; additional centers will be added in the coming year(s).

Conclusions

Our findings will affect clinical practice for pediatric patients with cancer by providing the first large-scale systematic comparison of the risk of subsequent cancers from proton compared with photon therapy.

Association between Radiation Dose and Local Failure in Recurrent High-Risk Neuroblastoma

PURPOSE/OBJECTIVE(S)

Historically, standard-of-care (SoC) for high-risk neuroblastoma recurrences is irradiation to 2160 cGy for gross or microscopic disease. Boosting gross disease to 3000-3600 cGy remains controversial. Prior reports have demonstrated worse local control with gross disease irradiated to <3000 cGy. We sought to evaluate whether higher radiation doses delivered to sites of recurrence affected local control.

MATERIALS/METHODS

We identified seventy-five high-risk neuroblastoma patients aged 6 months to 26 years that completed definitive treatment between 2007 and 2021 at two large academic centers. Only patients with distant recurrences treated with radiotherapy were included for analysis. Treatments were stratified into 1800-2160 cGy or 3000-3600 cGy dose levels. Local failure after irradiation was defined as progression within the radiation field after salvage RT. The Fine-Gray competing risk model was used to identify cumulative incidence of local failure (CILF) after irradiation with competing risk of death.

RESULTS

Thirteen patients experienced recurrence after completion of definitive treatment, representing 30 metastatic lesions. Thirteen lesions received 1800-2160 cGy and seventeen received 3000-3600 cGy. With a median follow-up of 42.0 months (IQR 30.8-60.8), local failure after irradiation occurred in 10% (3/30) of metastatic lesions. Median time to failure was 7 months. All three failures had been treated to 2160 cGy; two in the calvarium and one in the femur. There were no local failures among patients treated to 3000-3600 cGy. The 1-year and 2-year CILF for the low- versus high-dose levels were 15% versus 0% (p<0.01) and 25% versus 0% (p<0.01), respectively. Four of the 13 patients (31%) died at a median time of 12.5 months after first recurrence; all four had distant recurrences.

CONCLUSION

Dose-escalated irradiation ≥3000 cGy was associated with improved local control in recurrent high-risk neuroblastoma; prospective study and validation is warranted.

Is Robust Optimization Essential When Planning Pencil Beam Scanned Proton Therapy for Intracranial Lesions?

PURPOSE/OBJECTIVE(S)

Creating intensity modulated proton therapy (IMPT) plans usually involves a robust optimization step to account for uncertainties in proton range and positioning instead of using the PTV margins typically seen in photon IMRT planning. Because robust optimization adds significant planning time per iteration, and proton planning typically involves many iterations to obtain an optimal plan, this project evaluates whether a PTV approach can be used to more efficiently create plans for intracranial lesions by comparing plan quality from both approaches to determine if they produce equivalent plans.

MATERIALS/METHODS

Five patients with intracranial lesions treated with IMPT at our center were randomly chosen for this study. 3-4 beams were used to treat CTVs ranging between 46 and 246 cc. Patients were treated on a Mevion S250i single-vault proton machine with Hyperscan. Static blocks (7mm conformed to the CTV) were used for all cases and plans were created in a treatment planning system using robustness criteria of 3mm (position uncertainty) and 3.5% (range uncertainty). For each patient, the CTV was uniformly grown by 3 mm to create a PTV. The optimization criteria used in the clinical plan were used as baseline to create two plans - one using robust optimization for CTV coverage and one without robust optimization for PTV coverage. A script was used to time two otherwise identical optimization runs. All plans were normalized so that the prescription was delivered to 95% of the CTV. The plan was robustly evaluated under conditions of 3.5% range uncertainty and 2mm positional uncertainty. For each nominal plan, the CTV dose heterogeneity and conformity as well as the following dose metrics were collected: CTV D99% and D98%, Normal Brain V100%, V90%, V80%, V50% as well as overall plan Dmax (to 0.03cc). For each plan, the minimum CTV D99 and maximum Brain Dmax were also collected for the robust evaluation scenarios. All collected metrics were compared between the robust CTV-based and non-robust PTV-based plans using paired t-tests with 5% significance.

RESULTS

For the five cases investigated here, all dosimetric metrics investigated were not significantly different between the CTV-based and PTV-based plans except for the plan maximum dose (CTV-based: 104.6% Rx - 110.0% Rx, PTV-based: 105.6% Rx-110.6% Rx, p = 0.029). The optimization times were also significantly different, averaging 1532 s for CTV-based plans versus 252 s for the PTV-based plans (p = 0.004).

CONCLUSION

For the plans investigated here, non-robust PTV planning approach creates plans of very similar quality to a robust CTV-based plan, while having significantly shorter planning times.

CT-on-Rails Utilization for Image Guidance and Plan Adaptation at a Single-Room Proton Therapy Center

PURPOSE/OBJECTIVE(S)

In-room CT-on-rails is a relatively rare imaging modality in proton therapy. This work evaluated the utilization of CT-on-rails (CTOR) for image guidance and plan adaptation at a single-room proton therapy center.

MATERIALS/METHODS

All patients treated from the proton center beginning treatment to the current date were evaluated (May 2021 - January 2023). Patients were treated using a Mevion S250i scanning beam proton therapy system with an in-room Definition Edge CTOR. The image guidance technique utilized for each patient was evaluated (CTOR, orthogonal planar kV imaging, or both). For patients who required a new CT for plan adaptation, the use of CT images from CTOR or a new simulation CT was assessed.

RESULTS

Of the 132 patients treated over the evaluated time period, 56.0% utilized CTOR for image guidance at some point during their treatment. 21.2% utilized CTOR as the only image guidance technique, while 34.8% utilized CTOR in combination with kV planar imaging. For 43.9% of patients, only orthogonal planar kV imaging was utilized. Head and neck treatment sites most often utilized CTOR alone as an image guidance technique, while central nervous system sites most often utilized kV planar imaging alone. Of the patients who required new CT imaging for plan adaptation, 75.0% utilized CTOR images. Some reasons for patients not being able to utilize CTOR imaging for re-planning were the need for 4DCT imaging (which was not available on the CTOR) or the need to re-make immobilization devices (such as thermoplastic masks due to becoming loose).

CONCLUSION

CTOR was shown to be utilized for image guidance in the majority of patients receiving proton therapy at a single-room proton therapy center. CTOR was able to be used for plan adaptation in a large majority of patients, eliminating the need to schedule additional CT simulation appointments for these patients.

Mental health disorders are more common in patients with Hodgkin lymphoma and may negatively impact overall survival

BACKGROUND

Long-term mental health outcomes were characterized in patients who were diagnosed with Hodgkin lymphoma (HL), and risk factors for the development of mental health disorders were identified.

METHODS

Patients who were diagnosed with HL between 1997 and 2014 were identified in the Utah Cancer Registry. Each patient was matched with up to five individuals from a general population cohort identified within the Utah Population Database, a unique source of linked records that includes patient and demographic data.

RESULTS

In total, 795 patients who had HL were matched with 3575 individuals from the general population. Compared with the general population, patients who had HL had a higher risk of any mental health diagnosis (hazard ratio, 1.77; 95% confidence interval, 1.57-2.00). Patients with HL had higher risks of anxiety, depression, substance-related disorders, and suicide and intentional self-inflicted injuries compared with the general population. The main risk factor associated with an increased risk of being diagnosed with mental health disorders was undergoing hematopoietic stem cell transplantation, with a hazard ratio of 2.06 (95% confidence interval, 1.53-2.76). The diagnosis of any mental health disorder among patients with HL was associated with a detrimental impact on overall survival; the 10-year overall survival rate was 70% in patients who had a mental health diagnosis compared with 86% in those patients without a mental health diagnosis (p < .0001).

CONCLUSIONS

Patients who had HL had an increased risk of various mental health disorders compared with a matched general population. The current data illustrate the importance of attention to mental health in HL survivorship, particularly for patients who undergo therapy with hematopoietic stem cell transplantation.

Acute lymphoblastic leukemia

The survival of patients with acute lymphoblastic leukemia (ALL) has improved significantly with the use of intensive multimodality treatment regimens including chemotherapy, high-dose chemotherapy and stem cell rescue, and radiation therapy when indicated. This report summarizes the treatment strategies, especially radiation therapy in the Children's Oncology Group for children with ALL. Currently, radiation therapy is only indicated for children with high-risk CNS involvement at diagnosis or relapse, testicular relapse and as part of the conditioning regimen for hematopoietic stem cell transplantation. Future research strategies regarding the indications for and dosages of radiation therapy and novel radiation techniques are discussed.

Factors Associated with Nodal Pathologic Complete Response Among Breast Cancer Patients Treated with Neoadjuvant Chemotherapy: Results of CALGB 40601 (HER2+) and 40603 (Triple-Negative) (Alliance)

BACKGROUND

De-escalation of axillary surgery after neoadjuvant chemotherapy (NAC) requires careful patient selection. We seek to determine predictors of nodal pathologic complete response (ypN0) among patients treated on CALGB 40601 or 40603, which tested NAC regimens in HER2+ and triple-negative breast cancer (TNBC), respectively.

PATIENTS AND METHODS

A total of 760 patients with stage II-III HER2+ or TNBC were analyzed. Those who had axillary surgery before NAC (N = 122), or who had missing pretreatment clinical nodal status (cN) (N = 58) or ypN status (N = 41) were excluded. The proportion of patients with ypN0 disease was estimated for those with and without breast pathologic complete response (pCR) according to pretreatment nodal status.

RESULTS

In 539 patients, the overall ypN0 rate was 76.3% (411/539) to 93.2% (245/263) in patients with breast pCR and 60.1% (166/276) with residual breast disease (RD) (P < 0.0001). For patients who were cN0 pretreatment, the ypN0 rate was 88.8% (214/241), 96.3% (104/108) with breast pCR, and 82.7% (110/133) with RD. For patients who were cN1, 66.2% (157/237) converted to ypN0, 91.7% (111/121) with breast pCR and 39.7% (46/116) with RD. For patients who were cN2/3, 65.6% (40/61) converted to ypN0, 88.2% (30/34) with breast pCR and 37.0% (10/27) with RD. On multivariable analysis, only pretreatment clinical nodal status and breast pCR/RD were associated with ypN0 status (both P < 0.0001).

CONCLUSIONS

Breast pCR and pretreatment nodal status are predictive of ypN0 axillary nodal involvement, with < 5% residual nodal disease among cN0 patients who experience breast pCR. These findings support the incorporation of axillary surgery de-escalation strategies into NAC trials.

Radiation therapy and secondary malignancy in Li-Fraumeni syndrome: A hereditary cancer registry study

Background

Li‐Fraumeni Syndrome (LFS) is a rare cancer‐predisposing condition caused by germline mutations in TP53. Conventional wisdom and prior work has implied an increased risk of secondary malignancy in LFS patients treated with radiation therapy (RT); however, this risk is not well‐characterized. Here we describe the risk of subsequent malignancy and cancer‐related death in LFS patients after undergoing RT for a first or second primary cancer.

Methods

We reviewed a multi‐institutional hereditary cancer registry of patients with germline TP53 mutations who were treated from 2004 to 2017. We assessed the rate of subsequent malignancy and death in the patients who received RT (RT group) as part of their cancer treatment compared to those who did not (non‐RT group).

Results

Forty patients with LFS were identified and 14 received RT with curative intent as part of their cancer treatment. The median time to follow‐up after RT was 4.5 years. Fifty percent (7/14) of patients in the curative‐intent group developed a subsequent malignancy (median time 3.5 years) compared to 46% of patients in the non‐RT group (median time 5.0 years). Four of seven subsequent malignancies occurred within a prior radiation field and all shared histology with the primary cancer suggesting recurrence rather than new malignancy.

Conclusion

We found that four of14 patients treated with RT developed in‐field malignancies. All had the same histology as the primary suggesting local recurrences rather than RT‐induced malignancies. We recommend that RT should be considered as part of the treatment algorithm when clinically indicated and after multidisciplinary discussion.

5-Year Update of a Multi-Institution, Prospective Phase 2 Hypofractionated Postmastectomy Radiation Therapy Trial

PURPOSE

Hypofractionation in the setting of postmastectomy radiation (PMRT) is not currently the standard of care in most countries. Here we present a 5-year update of our multi-institutional, phase 2 prospective trial evaluating a novel 15-day hypofractionated PMRT regimen.

METHODS AND MATERIALS

Patients were enrolled to receive 3.33 Gy daily to the chest wall (or reconstructed breast) and regional lymphatics in 11 fractions with an optional 4-fraction mastectomy scar boost. The primary endpoint was freedom from grade 3 or higher late non-reconstruction-related radiation toxicities. Toxicities were scored using Common Terminology Criteria for Adverse Events v4.0. Secondary endpoints included local and locoregional recurrence rates, cosmesis, and reconstruction complications.

RESULTS

After enrolling 69 patients with stage II-IIIa breast cancer, 67 women were eligible for analysis. At a median follow up of 54 months, there were no acute or late grade 3 and 4 nonreconstruction reported toxicities. The grade 2 or greater late toxicity rate was only 12% and comprised grade 2 pain, fatigue, and lymphedema that persisted beyond 6 months after completion of radiation therapy. Only 3 women (4.6%) experienced a chest wall or nodal recurrence as a first site of relapse. Freedom from local failure, including local failure after distant relapse, was 92% at 5 years, and the 5-year overall survival was 90%.

CONCLUSIONS

This is the first prospective trial conducted in the United States to demonstrate the safe and effective use of hypofractionated PMRT. We have demonstrated a low complication rate while achieving excellent local control. Toxicity was better than anticipated based on previously published series of PMRT toxicities. Although our fractionation was novel, the radiobiological equivalent dose is similar to other hypofractionation schedules. This trial was the basis for the creation of Alliance A221505 (RT CHARM), which is currently accruing patients in a phase 3 randomized design.

The radiation dose-response of non-retroperitoneal soft tissue sarcoma with positive margins: An NCDB analysis

OBJECTIVES

Positive margins can increase the risk of local recurrence of soft tissue sarcomas (STS). Utilizing a national registry, we investigated patterns of care and overall survival (OS) of patients with margin-positive non-retroperitoneal STS who received preoperative radiation therapy, adjuvant radiation therapy, or both.

METHODS

Adult patients with non-retroperitoneal STS who underwent resection and RT from 2004 to 2015 were included. Kaplan-Meier, log-rank analysis, and Cox regression analysis were performed.

RESULTS

We identified 5726 patients. Most had a tumor size >5 cm (60%), grade 3 disease (67%), and microscopically positive margins (57%). Compared to ≤50.4 Gy, a dose of 66 to 69.99 Gy was associated with decreased risk of death on multivariate analysis (HR 0.69, 95%; CI, 0.50-0.94). Receipt of a boost was associated with decreased risk of death on univariate analysis (HR 0.54, 95%; CI, 0.29-0.99). In patients with grade 2 to 3 tumors without the gross disease, there was an OS benefit associated with a boost on multivariate analysis (HR 0.39, 95%; CI, 0.16-0.97).

CONCLUSION

This analysis appears to show an OS benefit of dose escalation to 66 to 69 Gy for margin-positive non-retroperitoneal STS. A Postoperative boost is associated with higher OS in grade 2 to 3 STS without the gross disease.

Myxoid glioneuronal tumor, PDGFRA p.K385-mutant: clinical, radiologic, and histopathologic features

"Myxoid glioneuronal tumor, PDGFRA p.K385-mutant" is a recently described tumor entity of the central nervous system with a predilection for origin in the septum pellucidum and a defining dinucleotide mutation at codon 385 of the PDGFRA oncogene replacing lysine with either leucine or isoleucine (p.K385L/I). Clinical outcomes and optimal treatment for this new tumor entity have yet to be defined. Here, we report a comprehensive clinical, radiologic, and histopathologic assessment of eight cases. In addition to its stereotypic location in the septum pellucidum, we identify that this tumor can also occur in the corpus callosum and periventricular white matter of the lateral ventricle. Tumors centered in the septum pellucidum uniformly were associated with obstructive hydrocephalus, whereas tumors centered in the corpus callosum and periventricular white matter did not demonstrate hydrocephalus. While multiple patients were found to have ventricular dissemination or local recurrence/progression, all patients in this series remain alive at last clinical follow-up despite only biopsy or subtotal resection without adjuvant therapy in most cases. Our study further supports "myxoid glioneuronal tumor, PDGFRA p.K385-mutant" as a distinct CNS tumor entity and expands the spectrum of clinicopathologic and radiologic features of this neoplasm.

The value of high-dose radiotherapy in intracranial ependymoma

BACKGROUND

We sought to evaluate the impact of adjuvant radiotherapy dose on overall survival (OS) after surgical resection for localized intracranial ependymoma.

PROCEDURE

The National Cancer Database (NCDB) was queried from 2004 to 2015 for patients of all ages with intracranial WHO grade II to III ependymoma treated with surgery and 4500 to 7000 cGy of adjuvant radiotherapy. Pearson χ² test and multivariate logistic regression analyses were used to assess clinicodemographic factors and patterns of care. After propensity-score matching, OS was assessed with Kaplan-Meier analyses and doubly robust estimation with multivariate Cox proportional hazards modeling.

RESULTS

Of the 1153 patients meeting criteria, 529 (46%) received ≤ 5400 cGy and 624 (54%) received > 5400 cGy. At a median follow-up of 54.5 months, an OS benefit was observed for > 5400 cGy in pediatric patients aged 2-18 years (hazard ratio [HR] 0.53; 95% confidence interval [CI] 0.28-0.99, P = 0.047). No OS difference was found between ≤ 5400 cGy and > 5400 cGy in pediatric patients aged < 2 years (P = 0.819) or in adults (P = 0.180). Increasing age, WHO grade III, subtotal resection, and receipt of chemotherapy portended worse OS. Age 2 to 18 years, WHO III grade, supratentorial location, and receipt of chemotherapy were associated with receiving > 5400 cGy.

CONCLUSION

Adjuvant radiotherapy dose > 5400 cGy was associated with improved OS for children aged 2-18 years with WHO grade II-III intracranial ependymoma. No OS benefit was found with > 5400 cGy in adults or children less than two years of age.

Demographics, stage distribution, and relative roles of surgery and radiotherapy on survival of persons with primary prostate sarcomas

Background

Primary prostate sarcomas (PPS) are rare. Outcomes for this cancer have not been well characterized.

Materials and Methods

Subjects with a PPS diagnosed between 1973 and 2014 were identified in the SEER database. Subjects were stratified by disease stage and types of therapies received. Disease‐specific survival (DSS) and Overall survival (OS) was estimated by Kaplan‐Meier analysis and cohorts were compared with a univariate and multivariable Cox regression.

Results

The incidence of PPS among all prostate cancer diagnoses was 0.02%. Subjects younger than age 26 years at diagnosis represented 29% of cases, and 32% of primary prostate sarcomas were rhabdomyosarcoma histology.

Rhabdomyosarcoma Histologies

The median age at diagnosis was 9 years. Between age 0‐25 years rhabdomyosarcoma accounted for 96.4% of primary prostate sarcoma diagnoses, after age 25 rhabdomyosarcoma represented 15% of new diagnoses. The 10‐year DSS and OS for rhabdomyosarcoma was 47% and 44%.

Non‐Rhabdomyosarcoma Histologies

The median age at diagnosis was 71 years. The most common diagnoses were leiomyosarcoma (33%) and carcinosarcoma (28%). Localized, regional, or distant disease occurred in 40%, 34%, and 26% of cases. The 10‐year DSS and OS were 26% and 14%. In locally advanced cases, RT added to surgery trended toward improved DSS (P = 0.10).

Conclusions

Disease‐specific survival and OS for non‐rhabdomyosarcoma histologies appear inferior to those of rhabdomyosarcoma. The addition of RT to surgical resection may improve DSS in locally advanced non‐rhabdomyosarcoma. This is the largest report of the incidence, stage distribution, and survival for this extremely rare urologic malignancy providing valuable prognostic information.

Skin dose estimation using virtual structures for Contura Multi-Lumen Balloon breast brachytherapy

PURPOSE

To propose a workflow that uses ultrasound (US)-measured skin-balloon distances and virtual structure creations in the treatment planning system to evaluate the maximum skin dose for patients treated with Contura Multi-Lumen Balloon applicators.

METHODS AND MATERIALS

Twenty-three patients were analyzed in this study. CT and US were used to investigate the interfractional skin-balloon distance variations. Virtual structures were created on the planning CT to predict the maximum skin doses. Fitted curves and its equation can be obtained from the skin-balloon distance vs. maximum skin dose plot using virtual structure information. The fidelity of US-measured skin distance and the skin dose prediction using virtual structures were assessed.

RESULTS

The differences between CT- and US-measured skin-balloon distances values had an average of -0.5 ± 1.1 mm (95% confidence interval [CI] = -1.0 to 0.1 mm). Using virtual structure created on CT, the average difference between the predicted and the actual dose overlay maximum skin dose was -1.7% (95% CI = -3.0 to -0.4%). Furthermore, when applying the US-measured skin distance values in the virtual structure trendline equation, the differences between predicted and actual maximum skin dose had an average of 0.7 ± 6.4% (95% CI = -2.3% to 3.7%).

CONCLUSIONS

It is possible to use US to observe interfraction skin-balloon distance variation to replace CT acquisition. With the proposed workflow, based on the creation of virtual structures defined on the planning CT- and US-measured skin-balloon distances, the maximum skin doses can be reasonably estimated.

The Role of Radiation in All Stages of Nodular Lymphocytic Predominant Hodgkin Lymphoma

BACKGROUND

The goal of this study was to assess the survival differences seen in early-stage and advanced-stage nodular lymphocytic predominant Hodgkin lymphoma (NLPHL) based on treatment modality.

PATIENTS AND METHODS

The National Cancer Database was queried to identify patients diagnosed with NLPHL between 2004 and 2012. Overall survival (OS) was determined using univariate and multivariate Cox regression analysis. Kaplan-Meier and log-rank analysis were used to estimate differences in OS between treatment groups.

RESULTS

A total of 1968 patients were identified for analysis, consisting of stage I (40.4%), stage II (29.3%), stage III (22.3%), and stage IV (8.0%) disease. The median age of patients was 46 years. The following factors were predictive of radiotherapy (RT) omission in treatment: increasing age, black race, Medicare insurance, chemotherapy use, stage II to IV disease, and the presence of B-symptoms. On survival analysis, RT was associated with prolonged OS in all stages of NLPHL (50.1 vs. 42.4 months; P < .01). The OS benefit of RT persisted on multivariate analysis (hazard ratio, 0.37; P < .01). On subset analysis, RT was associated with prolonged OS in early disease (49.8 vs. 45.5 months; P < .01), whereas a trend towards an OS benefit was observed in advanced-stage (54.1 vs. 39.6 months; P = .06) NLPHL. Radiotherapy was also associated with prolonged OS among patients with B-symptoms (49.0 vs. 42.6 months; P < .01).

CONCLUSION

The use of RT in NLPHL is less likely among those with advanced-stage disease and B-symptoms. However, we found RT to be associated with prolonged OS in all stages of NLPHL, including those with B-symptoms.

Risk of secondary malignancies after radiation therapy for breast cancer: Comprehensive results

GOALS

To assess risks of secondary malignancies in breast cancer patients who received radiation therapy compared to patients who did not.

METHODS

The SEER database was used to identify females with a primary diagnosis of breast cancer as their first malignancy, during 1973-2008. We excluded patients with metastatic disease, age <18 years, no definitive surgical intervention, ipsilateral breast cancer recurrence, or who developed a secondary malignancy within 1 year of diagnosis. Standardized incidence ratios and absolute excess risk were calculated using SEER*Stat, version 8.2.1 and SAS, version 9.4.

PRINCIPLE RESULTS

There were 374,993 patients meeting the inclusion criteria, with 154,697 who received radiation therapy. With a median follow-up of 8.9 years, 13% of patients (49,867) developed a secondary malignancy. The rate of secondary malignancies was significantly greater than the endemic rate in breast cancer patients treated without radiation therapy, (O/E 1.2, 95% CI 1.19-1.22) and with radiation therapy (O/E 1.33, 95% CI 1.31-1.35). Approximately 3.4% of secondary malignancies were attributable to radiation therapy. The increased risk of secondary malignancies in breast cancer patients treated with radiation therapy compared to those without was significant regardless of age at breast cancer diagnosis (p < 0.01) and more pronounced with longer latency periods.

CONCLUSION

There was an increased risk of secondary malignancies for breast cancer patients both with and without radiation therapy compared to the general population. There was an increased risk in specific sites for patients treated with radiation therapy. This risk was most evident in young patients and who had longer latency periods.

Breast Reconstruction With Postmastectomy Radiation: Choices and Tradeoffs

The Oncology Grand Rounds series is designed to place original reports published in the Journal into clinical context. A case presentation is followed by a description of diagnostic and management challenges, a review of the relevant literature, and a summary of the authors' suggested management approaches. The goal of this series is to help readers better understand how to apply the results of key studies, including those published in Journal of Clinical Oncology, to patients seen in their own clinical practice. A 45-year-old premenopausal woman presented with multifocal cancer in the right breast, with lesions at 1:00 and 4:00, the largest measuring approximately 3 cm on exam, and multiple palpable right axillary lymph nodes. A core biopsy confirmed invasive ductal carcinoma, grade 2 of 3, that was estrogen receptor positive, progesterone receptor positive, and HER2 negative. Fine needle aspiration of a right axillary node confirmed metastatic carcinoma. A positron emission tomography (PET)/ computed tomography done before starting chemotherapy demonstrated an absence of metastatic disease with expected avidity in two separate breast masses and multiple conglomerated 1-2 cm level I and II axillary lymph nodes. She received neoadjuvant chemotherapy with doxorubicin plus cyclophosphamide, followed by paclitaxel, and had a complete clinical response with resolution of the breast and axillary masses on exam. A repeat PET/computed tomography demonstrated reduced size of the breast and axillary disease, and no significant residual PET avidity. Her breast surgeon recommended a right mastectomy with axillary node dissection. As part of her multidisciplinary treatment plan, she consulted with two plastic surgeons to discuss reconstruction options. Plastic Surgeon A advised placement of an implant at the time of mastectomy while Surgeon B contrasted the pros and cons of an autologous transverse rectus abdominis muscle flap reconstruction with an implant based reconstruction. Surgeon B believed that autologous reconstruction would yield the best long-term cosmetic outcome. Before making her surgery decision, the patient consulted with a radiation oncologist to discuss the effect radiation may have on her reconstruction outcome.

Hypofractionated Postmastectomy Radiation Therapy Is Safe and Effective: First Results From a Prospective Phase II Trial

Purpose Conventionally fractionated postmastectomy radiation therapy (PMRT) takes approximately 5 to 6 weeks. Data supporting hypofractionated PMRT is limited. We prospectively evaluated a short course of hypofractionated PMRT, in which therapy was completed in 15 treatment days. Patients and Methods We delivered PMRT at a dose of 36.63 Gy in 11 fractions of 3.33 Gy over 11 days to the chest wall and the draining regional lymph nodes, followed by an optional mastectomy scar boost of four fractions of 3.33 Gy. Our primary end point was freedom from any grade 3 or higher toxicities. We incorporated early stopping criteria on the basis of predefined toxicity thresholds. Results We enrolled 69 women with stage II to IIIa breast cancer, of whom 67 were eligible for analysis. After a median follow-up of 32 months, there were no grade 3 toxicities. There were 29 reported grade 2 toxicities, with grade 2 skin toxicities being the most frequent (16 of 67; 24%). There were two patients with isolated ipsilateral chest wall tumor recurrences (2 of 67; crude rate, 3%). Three-year estimated local recurrence-free survival was 89.2% (95% CI, 0.748 to 0.956). The 3-year estimated distant recurrence-free survival was 90.3% (95% CI, 0.797 to 0.956). Forty-one patients had chest wall reconstructions; three had expanders removed for infection before radiation therapy. The total rate of implant loss or failure was 24% (9 of 38), and the unplanned surgical correction rate was 8% (3 of 38), for a total complication rate of 32%. Conclusion To our knowledge, our phase II prospective study offers one of the shortest courses of PMRT reported, delivered in 11 fractions to the chest wall and nodes and 15 fractions inclusive of a boost. We demonstrated low toxicity and high local control with this schedule. On the basis of our data, we have designed a cooperative group phase III prospective, randomized trial of conventional versus hypofractionated PMRT that will activate soon.

Outcomes and utilization of postmastectomy radiotherapy for T3N0 breast cancers

BACKGROUND

The role of postmastectomy radiotherapy (PMRT) for women with pT3N0M0 breast cancer is controversial. We sought to determine the benefit of PMRT in this cohort using the National Cancer Database (NCDB).

METHODS

We analyzed women with pT3N0M0 breast cancer who received mastectomy with or without PMRT between 2004 and 2012. We excluded men, women ≤18 years, neoadjuvant or unknown radiation or chemotherapy status, unknown estrogen or progesterone receptor status, unknown surgical margin status, histology other than invasive ductal or lobular carcinoma, and if death occurred <3 months after diagnosis. A total of 4291 patients was included for analysis. Chi-squared analysis was used to compare patient characteristics. Univariate (UVA) and multivariate (MVA) Cox proportional hazards modeling was used to identify factors associated with survival. Propensity score matching was performed to address confounding variables. Survival analysis was performed using Kaplan-Meier and shared frailty models.

RESULTS

Of the 4291 women analyzed, 2030 (47%) received PMRT. On MVA, PMRT (HR 0.72, p < 0.001), chemotherapy (HR 0.51, p < 0.001), and hormone therapy (HR 0.63, p < 0.001) were associated with improved overall survival (OS). After propensity score matching, a matched cohort of 2800 women was analyzed. At 5 years, OS was 83.7% and 79.8% with and without PMRT, respectively (p < 0.001). This difference in OS benefit increased with time. At 10 years, OS was 67.4% and 59.2% with and without PMRT, respectively.

CONCLUSIONS

PMRT was associated with improved OS in women with pT3N0M0 breast cancer, which strongly suggests PMRT may provide a survival advantage and should be considered.

Post-mastectomy Radiotherapy for pT3N0 Breast Cancers: A Retrospective, Multi-Institution Review

The role of post-mastectomy radiotherapy for pT3N0 breast cancers remains undefined. The purpose of this study was to report institutional outcomes for women with pT3N0 breast cancers treated with and without post-mastectomy radiotherapy. We collected data from two large tumor registries on pT3N0 breast cancers diagnosed between 1985 and 2014. Kaplan-Meier estimates were used to analyze freedom from local-regional recurrence (FFLR), relapse free survival, and overall survival. This analysis identified 93 women with pT3N0 breast cancers. Of these, 53 received post-mastectomy radiotherapy and 40 did not. Median follow-up was 6.2 years and 5.3 years in the non-post-mastectomy radiotherapy and post-mastectomy radiotherapy cohorts, respectively. Women not undergoing post-mastectomy radiotherapy were more likely to be diagnosed in the 1980s and 1990s and were less likely to receive systemic therapies than women receiving post-mastectomy radiotherapy (p < 0.05). There was a trend toward increased FFLR in the women receiving post-mastectomy radiotherapy (p = 0.15). FFLR in the post-mastectomy radiotherapy cohort was 98% at both 5 and 10 years. For women not receiving post-mastectomy radiotherapy, FFLR was 88% at both 5 and 10 years. Women not receiving post-mastectomy radiotherapy in our study had an isolated local-regional failure rate of 12% at 10 years, despite receiving inferior systemic treatment by current standards. Local-regional control after post-mastectomy radiotherapy for pT3N0 breast cancers was excellent. Further research is needed to define post-mastectomy radiotherapy indications for this patient population when receiving chemotherapy and endocrine therapy in line with current guidelines.

Brachytherapy Improves Survival in Stage III Endometrial Cancer With Cervical Involvement

PURPOSE

To evaluate the survival benefit of adding vaginal brachytherapy (BT) to pelvic external beam radiation therapy (EBRT) in women with stage III endometrial cancer.

METHODS AND MATERIALS

The National Cancer Data Base was used to identify patients with stage III endometrial cancer from 2004 to 2013. Only women who received adjuvant EBRT were analyzed. Women were grouped according to receipt of BT. Logistic regression modeling was used to identify predictors of receiving BT. Log-rank statistics were used to compare survival outcomes. Cox proportional hazards modeling was used to evaluate the effect of BT on survival. A propensity score-matched analysis was also conducted among women with cervical involvement.

RESULTS

We evaluated 12,988 patients with stage III endometrial carcinoma, 39% of whom received EBRT plus BT. Women who received BT were more likely to have endocervical or cervical stromal involvement (odds ratios 2.03 and 1.77; P<.01, respectively). For patients receiving EBRT alone, the 5-year survival was 66% versus 69% with the addition of BT at 5 years (P<.01). Brachytherapy remained significantly predictive of decreased risk of death (hazard ratio 0.86; P<.01) on multivariate Cox regression. The addition of BT to EBRT did not affect survival among women without cervical involvement (P=.84). For women with endocervical or cervical stromal invasion, the addition of BT significantly improved survival (log-rank P<.01). Receipt of EBRT plus BT was associated with improved survival in women with positive and negative surgical margins, and receiving chemotherapy did not alter the benefit of BT. Propensity score-matched analysis results confirmed the benefit of BT among women with cervical involvement (hazard ratio 0.80; P=.01).

CONCLUSIONS

In this population of women with stage III endometrial cancer the addition of BT to EBRT was associated with an improvement in survival for women with endocervical or cervical stromal invasion.

Abstract P3-12-08: Are different therapeutic approaches required after skin and nipple sparing mastectomies for locoregional control? A single institution's experience

Introduction

Nipple sparing (NSM) and skin sparing (SSM) mastectomies are gaining popularity. These procedures leave breast tissue at the skin/breast interface with the intent to better cosmesis. However, the impact of NSM versus SSM on risk of local recurrence in the remaining breast tissue is not well characterized, nor is the effect of post mastectomy radiotherapy (PMRT) in these patients.

Methods

A single institution retrospective study was conducted on women treated with NSM or SSM from 2005 to 2011 with follow up through 2015. Chest wall and chest wall or axillary recurrence were assessed. Factors associated with recurrence were examined. Kaplan Meier estimates and Cox proportional hazards models were used to analyze chest wall recurrence (CWR) and chest wall or axillary recurrence (CWAR), with CWAR as the primary outcome variable.

Results

This analysis identified 181 women who underwent a SSM (n=103, 58 (56%) with PMRT) or NSM (n=78, 35 (45%) with PMRT). Women undergoing SSM were older (56.0 ± 13.6 years, mean ± SD) than NSM (44.6 ± 11.3, p &lt;0.0001) while follow-up times were similar (4.91 ± 0.43 and 5.43 ± 0.27 respectively, p = 0.15). Women undergoing PMRT were younger (49.2 ± 13.6 vs 53.1 ± 13.9 years, p = 0.008) but more likely to present with lymphovascular space invasion (LVSI)(42% vs 16%, p = 0.0003 by Chi-square), and were more likely to receive chemotherapy (83% vs 47%, p &lt;0.0001). The majority of women (62%) in the group not receiving PMRT had stage I disease, and 79% were node negative. For those undergoing PMRT, 83% were stage II or III, and 69% were node positive (p &lt;0.0001 for both differences). Despite the higher apparent risk of the PMRT group, the total number of chest wall or axillary recurrences was similar (8 in PMRT, 6 in no PMRT). Event-free survival for CWAR at 5 years was 92% for PMRT and 96% for no PMRT (p=0.42) and at 7.5 years, 85% and 84% respectively (p=0.42). In univariate Cox regression among all patients, age was the strongest predictor of CWAR (HR = 1.103 per year of age, 95% CI 1.053-1.154, p&lt;0.0001). CWAR occurred in 2.6 % of NSM patients as compared with 11.8% of SSM patients (p=0.025 by Fisher's exact test). SSM versus NSM was associated with increased hazzard for CWAR with HR = 4.6 (95% CI 1.03-21, p=0.046) on univariate analysis. However, this apparent risk became non-significant (HR = 2.24, 95% CI 0.48 – 10.5) with adjustment for age. Other variables associated with CWAR on univariate analysis included receipt of chemotherapy (HR = 0.28, 0.09-0.86, p=0.027) and estrogen receptor positive status (HR = 0.34, 0.12-0.98, p=0.046) but these also became non-significant with adjustment for age. In multivariate Cox regression analysis, use of PMRT was associated with a non-significant higher risk of CWAR (HR = 1.45, 0.33-6.4, p=0.63 ) adjusting for age, LVSI, mastectomy type, stage, and ER status.

Conclusions

The risk of a chest wall or axillary recurrence for early stage breast cancer after a SSM or NSM appears to be low at five years. Radiation can likely be omitted in this group. Furthermore, despite presenting with more advanced disease, women who underwent PMRT experienced excellent locoregional control. Further research is needed on this topic.

Citation Format: Hopkins ZH, Frandsen J, Poruk KE, Agarwal J, Poppe MM. Are different therapeutic approaches required after skin and nipple sparing mastectomies for locoregional control? A single institution's experience. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P3-12-08.

Long-term life expectancy for children with ependymoma and medulloblastoma

OBJECTIVES

There is a paucity of long-term follow-up data for children with intracranial ependymoma (IE) and medulloblastoma (MB). What happens to these children 20, 30, or 40 years after diagnosis? Do they have potential for a normal lifespan? The purpose of this study was to ascertain the long-term survival potential in children with MB or IE who have survived 5 years from diagnosis.

METHODS

A retrospective analysis was conducted using the SEER Program. Children (ages 0-19 years) from 1973 to 2011 with a diagnosis of MB or IE were identified. A cohort was created of potentially cured patients who survived 5 years from diagnosis. Cox proportional hazards models and Kaplan-Meier estimates were utilized to analyze long-term survival.

RESULTS

We identified 876 patients with MB and 474 patients with IE who were alive 5 years from diagnosis. Patients with MB had a 30-year overall survival (OS) and cancer-specific survival (CSS) of 70.2% and 80.1%, respectively. Patients with IE had a 30-year OS and CSS of 57.3% and 68.8%, respectively. When comparing MB with IE, MB had improved CSS (P = 0.04) and trended toward increased OS (P = 0.10).

CONCLUSIONS

A significant number of deaths due to disease occur for several decades after treatment for both IE and MB. Despite this, the potential for long-term survival exists in 5-year survivors of both histologies. If alive at 5 years from diagnosis, patients with MB tend to have a lower risk of death from disease compared to those with IE.

Primary T cell central nervous system lymphoblastic lymphoma in a child: case report and literature review

PURPOSE

Primary central nervous system lymphoma (PCNSL) of T cell origin is rare in pediatric patients. We report a case of T cell PCNSL in a 12-year-old boy and review the literature to highlight the importance of brain biopsy to definitively establish the diagnosis when PCNSL is suspected.

CASE REPORT

A 12-year-old boy presented with worsening left-sided weakness, nausea, vomiting, headache, blurred vision, and diplopia. Magnetic resonance imaging revealed right parietal gyral thickening with faint meningeal contrast enhancement. No clear diagnosis was identified after serum testing, cerebrospinal fluid analysis, and cerebral angiography. To establish the diagnosis definitively, a right craniotomy and open, frameless stereotactic biopsy were performed, which yielded the diagnosis of lymphoblastic T cell lymphoma.

CONCLUSIONS

PCNSL of T cell origin in children remains poorly studied, with only 18 detailed cases reported over the last three decades, including this case. Establishing a definitive diagnosis of PCNSL is challenging, and a brain biopsy is often required to obtain enough tissue for pathological analysis. Increasing awareness and identification of children diagnosed with T cell PCNSL is needed to better understand the molecular biology of this disease and develop more standardized treatment regimens.

Abstract P1-15-25: Phase II trial of hypofractionated post mastectomy radiation

Purpose: The efficacy of irradiating the chest wall and draining lymph nodes after mastectomy in improving local regional control has been firmly established by multiple trials comparing mastectomy alone to mastectomy with postoperative radiation. The currently accepted standard of care involves 25 fractions of chest wall and nodal radiation plus an optional 5 fraction scar boost. Given recent publications with intact breast radiation demonstrating equivalence with shorter course radiation treatment, we sought to establish a short course of radiation for women post mastectomy that would be equivalent to conventional radiation in terms of local control and complications.

Methods: Starting in 2011, Stage II and III, unilateral breast cancer patients were prospectively consented to participate in our study at Rutgers Cancer Institute of New Jersey and the University of Utah. We designed a phase II non-inferiority trial, with plans to enroll 65 patients, allowing for a 18% loco-regional recurrence rate if the true rate is 10%. Patients were allowed to receive chemotherapy before or after adjuvant radiation with radiation starting 14-63 days after surgery or adjuvant chemotherapy. Patients underwent 3D simulation and were treated with ≥ 6MV photon radiation using 3D conformal tangents or intensity modulation. Regional nodal radiation was included when clinically appropriate with inclusion of internal mammary nodes at the treating provider’s discretion. The prescription dose was prescribed at 333cGy per day to the chest wall and regional nodes for 11 daily fractions followed by a recommend scar boost of 333cGy per day for 4 fractions. Chest wall PTV was keep within 90-115% of the prescribed dose, the maximum brachial plexus dose was keep below 3919cGy (107%) and no portion of the heart could receive &gt;2Gy/day. The maximum dose of the boost field was kept to 120% of the boost prescription. Any breast reconstruction technique was allowed, per institutional standard.

Results: 48 patients have thus far been enrolled with a median follow up interval of 17 months. Looking at the 43 patients with &gt; 4 months of follow-up, we have only seen a 4.7% grade 3 or greater acute or late toxicity rate, with one grade 3 wound complications, and one grade 3 fibrosis. There has been one chest wall recurrence, for a 2.3% local recurrence rate.

Conclusion: Early results would appear to show that hypofractionated post mastectomy radiation appears to be safe and feasible. Acute toxicity is less than anticipated, however it is too early make any conclusions on efficacy or late effects, with only 48 out of 65 patients enrolled. We hope to use the results of this phase II trial to design a randomized prospective trial comparing hypofractionated post mastectomy radiation to standard fraction.

Citation Format: Matthew M Poppe, Bruce G Haffty, Atif J Khan. Phase II trial of hypofractionated post mastectomy radiation [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P1-15-25.

A comparison of helical intensity-modulated radiotherapy, intensity-modulated radiotherapy, and 3D-conformal radiation therapy for pancreatic cancer

We assessed dosimetric differences in pancreatic cancer radiotherapy via helical intensity-modulated radiotherapy (HIMRT), linac-based IMRT, and 3D-conformal radiation therapy (3D-CRT) with regard to successful plan acceptance and dose to critical organs. Dosimetric analysis was performed in 16 pancreatic cases that were planned to 54 Gy; both post-pancreaticoduodenectomy (n = 8) and unresected (n = 8) cases were compared. Without volume modification, plans met constraints 75% of the time with HIMRT and IMRT and 13% with 3D-CRT. There was no statistically significantly improvement with HIMRT over conventional IMRT in reducing liver V35, stomach V45, or bowel V45. HIMRT offers improved planning target volume (PTV) dose homogeneity compared with IMRT, averaging a lower maximum dose and higher volume receiving the prescription dose (D100). HIMRT showed an increased mean dose over IMRT to bowel and liver. Both HIMRT and IMRT offer a statistically significant improvement over 3D-CRT in lowering dose to liver, stomach, and bowel. The results were similar for both unresected and resected patients. In pancreatic cancer, HIMRT offers improved dose homogeneity over conventional IMRT and several significant benefits to 3D-CRT. Factors to consider before incorporating IMRT into pancreatic cancer therapy are respiratory motion, dose inhomogeneity, and mean dose.

Results of the 2005-2008 Association of Residents in Radiation Oncology survey of chief residents in the United States: clinical training and resident working conditions

PURPOSE

To document clinical training and resident working conditions reported by chief residents during their residency.

METHODS AND MATERIALS

During the academic years 2005 to 2006, 2006 to 2007, and 2007 to 2008, the Association of Residents in Radiation Oncology conducted a nationwide survey of all radiation oncology chief residents in the United States. Chi-square statistics were used to assess changes in clinical training and resident working conditions over time.

RESULTS

Surveys were completed by representatives from 55 programs (response rate, 71.4%) in 2005 to 2006, 60 programs (75.9%) in 2006 to 2007, and 74 programs (93.7%) in 2007 to 2008. Nearly all chief residents reported receiving adequate clinical experience in commonly treated disease sites, such as breast and genitourinary malignancies; and commonly performed procedures, such as three-dimensional conformal radiotherapy and intensity-modulated radiotherapy. Clinical experience in extracranial stereotactic radiotherapy increased over time (p < 0.001), whereas clinical experience in endovascular brachytherapy (p <0.001) decreased over time. The distribution of gynecologic and prostate brachytherapy cases remained stable, while clinical case load in breast brachytherapy increased (p = 0.006). A small but significant percentage of residents reported receiving inadequate clinical experience in pediatrics, seeing 10 or fewer pediatric cases during the course of residency. Procedures involving higher capital costs, such as particle beam therapy and intraoperative radiotherapy, and infrequent clinical use, such as head and neck brachytherapy, were limited to a minority of institutions. Most residency programs associated with at least one satellite facility have incorporated resident rotations into their clinical training, and the majority of residents at these programs find them valuable experiences. The majority of residents reported working 60 or fewer hours per week on required clinical duties.

CONCLUSIONS

Trends in clinical training and resident working conditions over 3 years are documented to allow residents and program directors to assess their residency training.