Risk of second non-breast cancer after radiotherapy for breast cancer: a systematic review and meta-analysis of 762,468 patients

Frequency of Radiation Therapy-Induced Malignancies in Patients With Li-Fraumeni Syndrome and Early-Stage Breast Cancer and the Influence of Radiation Therapy Technique

PURPOSE

Breast cancer (BC) is the most common malignancy in female patients with Li-Fraumeni syndrome (LFS), a condition associated with an increased risk of various malignancies, including radiation therapy (RT)-induced malignancies (RIM) within previously irradiated areas. Our study aimed to assess the incidence of RIM in patients with LFS and early-stage BC treated with adjuvant RT, including the effect of RT dose and technique.

METHODS AND MATERIALS

We examined patients with a germline pathogenic/likely pathogenic TP53 variant diagnosed with early-stage BC and monitored by a hereditary cancer team at a single cancer center. The study endpoints included RIM frequency, the association of RIM with the dose and type of RT (2-dimensional [2D] RT, 3-dimensional [3D] RT, and intensity modulated RT [IMRT]), and BC recurrence.

RESULTS

We analyzed 48 patients with a median age of 39 years (range, 21-62). The majority (71%) had the TP53 R337H variant, and 87% were unaware of their LFS diagnosis at the time of BC treatment. Treatment modalities included mastectomy (62%), (neo)adjuvant chemotherapy (66%), and RT (62%), with RT being more common after breast-conserving surgery (87% vs 46% with mastectomy, P = .010). Among the 30 patients treated with RT, 10% developed RIM in the irradiated field, consisting of 3 soft tissue malignancies. RT dose (≤40.8 or >40.8 Gy) did not influence RIM occurrence, but the type of RT did. RIM was observed in 100% of cases with 2D RT (2/2), 50% with IMRT (1/2), and 0% with 3D RT (0/16) (P = .004).

CONCLUSIONS

Our study underscores a concerning rate of RIM after adjuvant RT, emphasizing the importance of a thorough risk-benefit evaluation before recommending RT, with preference for its avoidance if possible. Although subgroup sizes were limited, the risk of RIM appeared to be influenced by the RT technique, with higher rates observed with 2D RT and IMRT compared with 3D RT. Early TP53 testing is essential to guide the BC treatment plan.

Second primary non-breast cancers in young breast cancer survivors

PURPOSE

We evaluated the incidence, timing, and risk factors for second primary non-breast cancers (SPNBC) among young breast cancer (BC) survivors.

METHODS

This study included participants of the Young Women's BC Study (YWS) who were diagnosed with stage 0-III BC between 2006 and 2016 and age 40 or younger at diagnosis (N = 1,230). Patient characteristics, treatment information, and clinical events were collected via serial surveys. Tumor and treatment data were obtained from medical record review. Five- and 10-year risks of SPNBCs were estimated via the cumulative incidence function, considering death, metastasis, or second primary BC as competing events. Fine and Gray subdistribution hazard models estimated subdistribution hazard ratios (sHRs) and 95% confidence intervals (CI) for SPNBC risk based on risk factors including demographics, germline genetics, primary BC characteristics, and treatments.

RESULTS

Among 1,230 women, over a median follow-up of 10.1 years, 47 patients (4%) developed an SPNBC. Types of malignancy included melanoma (n = 10), thyroid (n = 10), ovarian (n = 4), sarcoma (n = 4), uterine (n = 3), rectal (n = 3), bladder (n = 2), cervical (n = 2), head/neck (n = 2), lung (n = 2), lymphoma (n = 2), pancreatic (n = 2), and renal (n = 1). Five and 10-year cumulative incidence were 1.4% and 3.2%, respectively. Median time between primary BC and SPNBC was 7.3 years. No patient factors, primary tumor characteristics, or treatments were statistically significantly associated with SPNBC in univariable or multivariable models.

CONCLUSION

In this population, five-year cumulative incidence was higher than that reported among healthy women under 50 years of age, highlighting the importance of long-term surveillance for new non-breast cancers in young adult BC survivors.

Benefit of respiratory gating in the Danish Breast Cancer Group partial breast irradiation trial

BACKGROUND AND PURPOSE

Partial breast irradiation (PBI)has beenthe Danish Breast Cancer Group(DBCG) standard for selected breast cancer patients since 2016 based onearlyresults from the DBCG PBI trial.During trial accrual, respiratory-gated radiotherapy was introduced in Denmark. This study aims to investigate the effect of respiratory-gating on mean heart dose (MHD).

PATIENTS AND METHODS

From 2009 to 2016 the DBCG PBI trial included 230 patientswith left-sided breast cancer receiving external beam PBI, 40 Gy/15 fractions/3 weeks.Localization of the tumor bed on the planning CT scan, the use of respiratory-gating, coverage of the clinical target volume (CTV), and doses to organs at risk were collected.

RESULTS

Respiratory-gating was used in 123 patients (53 %). In 176 patients (77 %) the tumor bed was in the upper and in 54 patients (23 %) in the lower breast quadrants. The median MHD was 0.37 Gy (interquartile range 0.26-0.57 Gy), 0.33 Gy (0.23-0.49 Gy) for respiratory-gating, and 0.49 Gy (0.31-0.70 Gy) for free breathing, p < 0.0001. MHD was < 1 Gy in 206 patients (90 %) and < 2 Gy in 221 patients (96 %). Respiratory-gating led to significantly lower MHD for upper-located, but not for lower-located tumor beds, however, all MHD were low irrespective of respiratory-gating. Respiratory-gating did not improve CTV coverage or lower lung doses.

CONCLUSIONS

PBI ensured a low MHD for most patients. Adding respiratory-gating further reduced MHD for upper-located but not for lower-located tumor beds but did not influence target coverage or lung doses. Respiratory-gating is no longer DBCG standard for left-sided PBI.

The Japanese breast cancer society clinical practice guidelines for radiation treatment of breast cancer, 2022 edition

The Breast Cancer Clinical Practice Guidelines, organized by the Japanese Breast Cancer Society (JBCS), were published in 2022. We present the English version of the Radiation Therapy (RT) section of the guidelines. The JBCS formed a task force to update the 2018 version of the JBCS Clinical Practice Guidelines. The Background Questions (BQs) contain the standard treatments for breast cancer in clinical practice, whereas the Clinical Questions (CQs) address daily clinical questions that remain controversial. Future Research Questions (FRQs) explore the subjects that are considered important issues, despite there being insufficient data for inclusion as CQs. The task force selected the 12 BQs, 8 CQs, and 6 FRQs for the RT section. For each CQ, systematic literature reviews and meta-analyses were conducted according to the Minds Manual for Guideline Development 2020, version 3.0. The recommendations, strength of recommendation, and strength of evidence for each CQ were determined based on systematic reviews and meta-analyses, and finalized by voting at the recommendation decision meeting.

Second primary cancers among females with a first primary breast cancer: a population-based study in Northern Portugal

PURPOSE

To estimate the incidence rate of second primary cancers (SPCs) and the cumulative incidence of metachronous [diagnosed > 2 months after a first primary cancer (FPC)] SPCs in patients with a breast FPC, and to compare the incidence of SPC [overall, synchronous (≤ 2 months of the FPC) and metachronous] with that expected in the general female population.

METHODS

A cohort of patients with a breast FPC from the North Region Cancer Registry of Portugal, diagnosed in 2000-2010 (n = 15,981), was followed to 31 December 2015 for synchronous and metachronous SPCs. Cumulative incidence of metachronous SPCs considering death as a competing event, and incidence rates and standardized incidence ratios of SPCs were estimated.

RESULTS

The diagnosis of an SPC occurred in 1229 (7.7%) of patients with a breast FPC. SPCs occurred mainly in the breast, followed by digestive organs, lung, thyroid, and female genital organs. Globally, patients with a breast FPC had a higher incidence for all types of cancer compared to the general female population, and in particular for cancers of the breast, stomach, colon, lung, lymphoma, uterus, and ovary. The 10-year cumulative incidence of metachronous SPCs following a breast FPC was 6.6% and the corresponding 10-year cumulative mortality was 26.2%.

CONCLUSION

In Portugal, patients with a breast FPC have a higher incidence of cancer compared to the general female population, highlighting important aspects of care, surveillance, and counselling among this growing number of patients.

Screening for lung cancer with computed tomography: protocol for systematic reviews for the Canadian Task Force on Preventive Health Care

PURPOSE

Lung cancer is the leading cause of cancer deaths in Canada, and because early cancers are often asymptomatic screening aims to prevent mortality by detecting cancer earlier when treatment is more likely to be curative. These reviews will inform updated recommendations by the Canadian Task Force on Preventive Health Care on screening for lung cancer.

METHODS

We will update the review on the benefits and harms of screening with CT conducted for the task force in 2015 and perform de novo reviews on the comparative effects between (i) trial-based selection criteria and use of risk prediction models and (ii) trial-based nodule classification and different nodule classification systems and on patients' values and preferences. We will search Medline, Embase, and Cochrane Central (for questions on benefits and harms from 2015; comparative effects from 2012) and Medline, Scopus, and EconLit (for values and preferences from 2012) via peer-reviewed search strategies, clinical trial registries, and the reference lists of included studies and reviews. Two reviewers will screen all citations (including those in the previous review) and base inclusion decisions on consensus or arbitration by another reviewer. For benefits (i.e., all-cause and cancer-specific mortality and health-related quality of life) and harms (i.e., overdiagnosis, false positives, incidental findings, psychosocial harms from screening, and major complications and mortality from invasive procedures as a result of screening), we will include studies of adults in whom lung cancer is not suspected. We will include randomized controlled trials comparing CT screening with no screening or alternative screening modalities (e.g., chest radiography) or strategies (e.g., CT using different screening intervals, classification systems, and/or patient selection via risk models or biomarkers); non-randomized studies, including modeling studies, will be included for the comparative effects between trial-based and other selection criteria or nodule classification methods. For harms (except overdiagnosis) we will also include non-randomized and uncontrolled studies. For values and preferences, the study design may be any quantitative design that either directly or indirectly measures outcome preferences on outcomes pertaining to lung cancer screening. We will only include studies conducted in Very High Human Development Countries and having full texts in English or French. Data will be extracted by one reviewer with verification by another, with the exception of result data on mortality and cancer incidence (for calculating overdiagnosis) where duplicate extraction will occur. If two or more studies report on the same comparison and it is deemed suitable, we will pool continuous data using a mean difference or standardized mean difference, as applicable, and binary data using relative risks and a DerSimonian and Laird model unless events are rare (< 1%) where we will pool odds ratios using Peto's method or (if zero events) the reciprocal of the opposite treatment arm size correction. For pooling proportions, we will apply suitable transformation (logit or arcsine) depending on the proportions of events. If meta-analysis is not undertaken we will synthesize the data descriptively, considering clinical and methodological differences. For each outcome, two reviewers will independently assess within- and across-study risk of bias and rate the certainty of the evidence using GRADE (Grading of Recommendations Assessment, Development, and Evaluation), and reach consensus.

DISCUSSION

Since 2015, additional trials and longer follow-ups or additional data (e.g., harms, specific patient populations) from previously published trials have been published that will improve our understanding of the benefits and harms of screening. The systematic review of values and preferences will allow fulsome insights that will inform the balance of benefits and harms.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42022378858.

Association of radiotherapy for stage I-III breast cancer survivors and second primary malignant cancers: a population-based study

PURPOSE

With life span extending, breast cancer survivors may face the possibility of developing second primary cancers (SPCs). The objective of this research is to investigate the risk factors, risk attribute to radiotherapy and the survivalship for SPCs.

METHODS

A total of 445 523 breast cancer patients were enrolled from Surveillance, Epidemiology, and End Results database in 2000-2018. The risk factors for SPCs development were confirmed by competing risk model, and then were integrated to the nomogram establishment. The cumulative incidence of SPCs including SBC (second breast cancer), SGC (second gynecological cancer), and SLC (second lung cancer) were estimated. The radiotherapy-associated risk for SPCs were evaluated by Poisson regression in radiotherapy and no-radiotherapy. Propensity score matching was used to reduce possible bias for survival comparison.

RESULTS

There were 57.63% patients in radiotherapy. The risk factors for developing SPCs were age, year, race, tumor size, stage, radiotherapy, grade, surgery, and histology. The cumulative incidence of SPCs was 7.75% in no-radiotherapy and 10.33% in radiotherapy. SLC, SBC, and SGC also appeared the similar results. The increased risk of developing SPCs were associated with radiotherapy in majority subgroups. The dynamic radiotherapy-associated risk for SPCs by age slightly increased risk was observed. Regardless radiotherapy or no-radiotherapy, the 10-year overall survival for SBC (radiotherapy: 59.41%; no-radiotherapy: 55.53%) and SGC (radiotherapy: 48.61%; no-radiotherapy: 35.53%) were worse than that among matched patients with only primary cancers.

CONCLUSIONS

Breast cancer survivors remained a high radiotherapy-associated risk for developing SPCs. The prognosis in radiotherapy was better than in no-radiotherapy for some specific SPCs. Largely attention should be paid to these patients.

Deep inspirational breast hold (DIBH) for right breast irradiation: Improved sparing of liver and lung tissue

Objective

To reduce liver and lung dose during right breast irradiation while maintaining optimal dose to the target volume. This dose reduction has the potential to decrease acute side effects and long-term toxicity.

Materials and Methods

16 patients treated with radiation therapy for localized carcinoma of the right breast were included retrospectively. For the planning CT, each patient was immobilised on an indexed board with the arms placed above the head. CT scans were acquired in free-breathing (FB) as well as with deep inspiration breath hold (DIBH). Both scans were acquired with the same length. Planning target volumes (PTV's) were created with a 5 mm margin from the respective clinical target volumes (CTV's) on both CT datasets. The liver was outlined as scanned. Dose metrics evaluated were as follows: differences in PTV coverage, dose to the liver (max, mean, V90%, V50%, V30%), dose to lung (mean, V20Gy, relative electron density) and dose to heart (Dmax). The p-values were calculated using Wilcoxon signed-rank tests. A p-value was significant when <0.05.

Results

Differences in PTV coverage between plans using FB and DIBH were less than 2 %. Maximum liver dose was significantly less using DIBH: 17.5 Gy versus FB: 40.3 Gy (p < 0.001). The volume of the liver receiving 10 % of the dose was significantly less using DIBH with 1.88 cm3 versus 72.2 cm3 under FB (p < 0.001). The absolute volume receiving 20 Gy in the right lung was larger using DIBH: 291 cm3 versus 230 cm3 under FB (p < 0.001) and the relative volume of lung receiving dose greater than 20 Gy was smaller with DIBH: 11.5 % versus 14 % in FB (p = 0.007). The relative electron density of lung was significantly less with DIBH: 0.59 versus 0.62 with FB, (p < 0.001). This suggests that the lung receives less dose due to its lower density when using DIBH.

Conclusion

Radiation of the right breast using DIBH spares liver and lung tissue significantly and thus carries the potential of best practice for right sided breast cancer.

Multinational Association of Supportive Care in Cancer (MASCC) clinical practice guidance for the prevention of breast cancer-related arm lymphoedema (BCRAL): international Delphi consensus-based recommendations

Background

Developing strategies to prevent breast cancer-related arm lymphoedema (BCRAL) is a critical unmet need because there are no effective interventions to eradicate it once it reaches a chronic state. Certain strategies such as prospective surveillance programs and prophylactic lymphatic reconstruction have been reported to be effective in clinical trials. However, a large variation exists in practice based on clinician preference, organizational standards, and local resources.

Methods

A two-round international Delphi consensus process was performed from February 27, 2023 to May 25, 2023 to compile opinions of 55 experts involved in the care and research of breast cancer and lymphoedema on such interventions.

Findings

Axillary lymph node dissection, use of post-operative radiotherapy, relative within-arm volume increase one month after surgery, greater number of lymph nodes dissected, and high body mass index were recommended as the most important risk factors to guide selection of patients for interventions to prevent BCRAL. The panel recommended that prospective surveillance programs should be implemented to screen for and reduce risks of BCRAL where feasible and resources allow. Prophylactic compression sleeves, axillary reverse mapping and prophylactic lymphatic reconstruction should be offered for patients who are at risk for developing BCRAL as options where expertise is available and resources allow. Recommendations on axillary management in clinical T1-2, node negative breast cancer patients with 1-2 positive sentinel lymph nodes were also provided by the expert panel. Routine axillary lymph node dissection should not be offered in these patients who receive breast conservation therapy. Axillary radiation instead of axillary lymph node dissection should be considered in the same group of patients undergoing mastectomy.

Interpretation

An individualised approach based on patients' preferences, risk factors for BCRAL, availability of treatment options and expertise of the healthcare team is paramount to ensure patients at risk receive preventive interventions for BCRAL, regardless of where they are receiving care.

Funding

This study was not supported by any funding. RJC received investigator grant support from the Australian National Health and Medical Research Council (APP1194051).

Risk of developing subsequent primary lung cancer after receiving radiation for breast cancer

Background

Radiotherapy (RT) is integral to breast cancer treatment, especially in the current era that emphasizes breast conservation. The aim of our study was to determine the incidence of subsequent primary lung cancer after RT exposure for breast cancer over a time span of 3 decades to quantify this risk over time as modern oncologic treatment continues to evolve.

Methods

The SEER (Surveillance, Epidemiology, and End Results) database was queried from 1988 to 2014 for patients diagnosed with nonmetastatic breast cancer. Patients who subsequently developed primary lung cancer were identified. Multivariable regression modeling was performed to identify independent factors associated with the development of lung cancer stratified by follow up intervals of 5 to 9 years, 10 to 15 years, and >15 years after breast cancer diagnosis.

Results

Of the 612,746 patients who met our inclusion criteria, 319,014 (52%) were irradiated. primary lung cancer developed in 5556 patients (1.74%) in the RT group versus 4935 patients (1.68%) in the non-RT group. In a multivariable model stratified by follow-up duration, the overall HR of developing subsequent ipsilateral lung cancer in the RT group was 1.14 (P = .036) after 5 to 9 years of follow-up, 1.28 (P = .002) after 10 to 15 years of follow-up, and 1.30 (P = .014) after >15 years of follow-up. The HR of contralateral lung cancer was not increased at any time interval.

Conclusions

The increased risk of developing a primary lung cancer secondary to RT exposure for breast cancer is much lower than previously published. Modern RT techniques may have contributed to the improved risk profile, and this updated study is important for counseling and surveillance of breast cancer patients.

Locoregional breast radiotherapy including IMN: optimizing the dose distribution using an automated non-coplanar VMAT-technique

BACKGROUND

Volumetric Modulated Arc Therapy (VMAT) offers better conformity, homogeneity and sparing of the heart and ipsilateral lung for locoregional radiotherapy in left-sided breast cancer compared to three-dimensional conformal radiotherapy (3D-CRT). However, conventional coplanar VMAT (cVMAT) can result in higher doses to the normal tissue on the contralateral side. This study investigates a non-coplanar VMAT-technique (ncVMAT) to mitigate this issue.

MATERIAL AND METHODS

CT series of 20 left sided breast cancer patients were included for planning of locoregional breast radiotherapy including internal mammary nodes (IMN). Three treatment plans; 3D-CRT, cVMAT and ncVMAT, were generated for each patient with a prescription dose of 40.05 Gy in 15 fractions. Both VMAT-techniques consisted of a single arc in the axial plane, while ncVMAT included an additional arc in the sagittal plane. All plans were optimized to cover the clinical target volume (CTV) by 38.05 Gy for the breast and 36.05 Gy for lymph nodes, with as low as possible dose to organs at risk.

RESULTS

Full CTV coverage was achieved for all plans. Both cVMAT and ncVMAT delivered more conformal and homogeneous target doses than 3D-CRT. Doses to the heart and ipsilateral lung were significantly lower with ncVMAT compared to both cVMAT and 3D-CRT. ncVMAT reduced doses to both the contralateral breast and lung compared to cVMAT and achieved levels similar to 3D-CRT for the contralateral breast and moderately higher doses for the contralateral lung. Delivery of high doses (>30 Gy) to the contralateral side was completely avoided with ncVMAT, contrary to the results for cVMAT and 3D-CRT.

CONCLUSION

ncVMAT reduced doses to the heart and ipsilateral lung as compared to both cVMAT and 3D-CRT. All contralateral dose metrics were reduced with the novel ncVMAT technique compared to cVMAT, and the mean contralateral breast doses were similar to 3D-CRT.

Vaping, Environmental Toxicants Exposure, and Lung Cancer Risk

Lung cancer (LC) is the second-most prevalent tumor worldwide. According to the most recent GLOBOCAN data, over 2.2 million LC cases were reported in 2020, with an estimated new death incident of 1,796,144 lung cancer cases. Genetic, lifestyle, and environmental exposure play an important role as risk factors for LC. E-cigarette, or vaping, products (EVPs) use has been dramatically increasing world-wide. There is growing concern that EVPs consumption may increase the risk of LC because EVPs contain several proven carcinogenic compounds. However, the relationship between EVPs and LC is not well established. E-cigarette contains nicotine derivatives (e.g., nitrosnornicotine, nitrosamine ketone), heavy metals (including organometal compounds), polycyclic aromatic hydrocarbons, and flavorings (aldehydes and complex organics). Several environmental toxicants have been proven to contribute to LC. Proven and plausible environmental carcinogens could be physical (ionizing and non-ionizing radiation), chemicals (such as asbestos, formaldehyde, and dioxins), and heavy metals (such as cobalt, arsenic, cadmium, chromium, and nickel). Air pollution, especially particulate matter (PM) emitted from vehicles and industrial exhausts, is linked with LC. Although extensive environmental exposure prevention policies and smoking reduction strategies have been adopted globally, the dangers remain. Combined, both EVPs and toxic environmental exposures may demonstrate significant synergistic oncogenicity. This review aims to analyze the current publications on the importance of the relationship between EVPs consumption and environmental toxicants in the pathogenesis of LC.

Beyond the heart in hypofractionated radiotherapy and in the transition from 3D to IMRT/VMAT

Background

The knowledge of the risks induced by radiation with hypofractionation regimens has only recently been estimated together with its implementation as a management standard. However, the dose to other risk organs with intensity-modulated radiation therapy (IMRT) or volumetric modulated arc therapy (VMAT) is not clear, that is why this is only a reference study of radiation doses to organs at risk in hypofractionation in our center.

Materials and methods

We completed a retrospective and observational analysis of 1398 patients treated with adjuvant hypofractionated radiotherapy from 2015 to 2018, using the clinical records and dose-volume histogram of patients treated with moderate hypofractionated adjuvant radiotherapy. To analyze the institutional experience on the dosimetry of the esophagus and liver as risk organs in the use of moderate adjuvant hypofractionated radiotherapy in breast cancer.

Results

The dosimetry of the esophagus was 3271 cGy DMax, 177 cGy DMed, 68 cGy D50%, 500 cGy DcMAX with 3D RT and 4124 cGy DMax, 1242 cGy DMed, 934.50 cGy D50%, 3213 cGy DcMAX with IMRT/VMAT and the dosimetry for the liver was for right breast cancer 466 cGy DMed, 102 cGy D50% and 8% V20, for left breast cancer 22 cGy DMed, 6.10 cGy D50% and 0.3% V20.

Conclusion

The statistically significant differences in irradiation show the lack of consensus on the optimal restrictions in hypofractionation regimens to reduce clinical sequela; consequently, the variability in the specification of each radiation oncologist is observed; standardization in our center can lead to improvement in the quality of treatments.

Recent advances progress in radiotherapy for breast cancer after breast-conserving surgery: a review

Adjuvant radiotherapy after breast-conserving surgery has become an integral part of the treatment of breast cancer. In recent years, the development of radiotherapy technology has made great progress in this field, including the comparison of the curative effects of various radiotherapy techniques and the performance of the segmentation times. The choice of radiotherapy technology needs to be co-determined by clinical evidence practice and evaluated for each individual patient to achieve precision radiotherapy. This article discusses the treatment effects of different radiotherapy, techniques, the risk of second cancers and short-range radiation therapy techniques after breast-conserving surgery such as hypo fractionated whole breast irradiation and accelerated partial breast irradiation. The choice of radiotherapy regimen needs to be based on the individual condition of the patient, and the general principle is to focus on the target area and reduce the irradiation of the normal tissues and organs. Short-range radiotherapy and hypofractionated are superior to conventional radiotherapy and are expected to become the mainstream treatment after breast-conserving surgery.

Electron stream effect in 0.35 Tesla magnetic resonance image guided radiotherapy for breast cancer

Purpose

This research aimed to analyze electron stream effect (ESE) during magnetic resonance image guided radiotherapy (MRgRT) for breast cancer patients on a MR-Linac (0.35 Tesla, 6MV), with a focus on the prevention of redundant radiation exposure.

Materials and methods

RANDO phantom was used with and without the breast attachment in order to represent the patients after breast conserving surgery (BCS) and those received modified radical mastectomy (MRM). The prescription dose is 40.05 Gy in fifteen fractions for whole breast irradiation (WBI) or 20 Gy single shot for partial breast irradiation (PBI). Thirteen different portals of intensity-modulated radiation therapy were created. And then we evaluated dose distribution in five areas (on the skin of the tip of the nose, the chin, the neck, the abdomen and the thyroid.) outside of the irradiated field with and without 0.35 Tesla. In addition, we added a piece of bolus with the thickness of 1cm on the skin in order to compare the ESE difference with and without a bolus. Lastly, we loaded two patients' images for PBI comparison.

Results

We found that 0.35 Tesla caused redundant doses to the skin of the chin and the neck as high as 9.79% and 5.59% of the prescription dose in the BCS RANDO model, respectively. For RANDO phantom without the breast accessory (simulating MRM), the maximal dose increase were 8.71% and 4.67% of the prescription dose to the skin of the chin and the neck, respectively. Furthermore, the bolus we added efficiently decrease the unnecessary dose caused by ESE up to 59.8%.

Conclusion

We report the first physical investigation on successful avoidance of superfluous doses on a 0.35T MR-Linac for breast cancer patients. Future studies of MRgRT on the individual body shape and its association with ESE influence is warranted.

External-Beam-Accelerated Partial-Breast Irradiation Reduces Organ-at-Risk Doses Compared to Whole-Breast Irradiation after Breast-Conserving Surgery

In order to evaluate organ-at-risk (OAR) doses in external-beam-accelerated partial-breast irradiation (APBI) compared to standard whole-breast irradiation (WBI) after breast-conserving surgery. Between 2011 and 2021, 170 patients with early breast cancer received APBI within a prospective institutional single-arm trial. The prescribed dose to the planning treatment volume was 38 Gy in 10 fractions on 10 consecutive working days. OAR doses for the contralateral breast, the ipsilateral, contralateral, and whole lung, the whole heart, left ventricle (LV), and the left anterior descending coronary artery (LAD), and for the spinal cord and the skin were assessed and compared to a control group with real-world data from 116 patients who underwent WBI. The trial was registered at the German Clinical Trials Registry, DRKS-ID: DRKS00004417. Compared to WBI, APBI led to reduced OAR doses for the contralateral breast (0.4 ± 0.6 vs. 0.8 ± 0.9 Gy, p = 0.000), the ipsilateral (4.3 ± 1.4 vs. 9.2 ± 2.5 Gy, p = 0.000) and whole mean lung dose (2.5 ± 0.8 vs. 4.9 ± 1.5 Gy, p = 0.000), the mean heart dose (1.6 ± 1.6 vs. 1.7 ± 1.4 Gy, p = 0.007), the LV V23 (0.1 ± 0.4 vs. 1.4 ± 2.6%, p < 0.001), the mean LAD dose (2.5 ± 3.4 vs. 4.8 ± 5.5 Gy, p < 0.001), the maximum spinal cord dose (1.5 ± 1.1 vs. 4.5 ± 5.7 Gy, p = 0.016), and the maximum skin dose (39.6 ± 1.8 vs. 49.1 ± 5.8 Gy, p = 0.000). APBI should be recommended to suitable patients to minimize the risk of secondary tumor induction and the incidence of consecutive major cardiac events.

Rectal Cancer after Prostate Radiation: A Complex and Controversial Disease

A small proportion of rectal adenocarcinomas develop in patients many years after the treatment of a previous cancer using pelvic radiation, and the incidence of these rectal cancers depends on the length of follow-up from the end of radiotherapy. The risk of radiation-associated rectal cancer (RARC) is higher in patients treated with prostate external beam radiotherapy than it is in patients treated with brachytherapy. The molecular features of RARC have not been fully investigated, and survival is lower compared to non-irradiated rectal cancer patients. Ultimately, it is unclear whether the worse outcomes are related to differences in patient characteristics, treatment-related factors, or tumor biology. Radiation is widely used in the management of rectal adenocarcinoma; however, pelvic re-irradiation of RARC is challenging and carries a higher risk of treatment complications. Although RARC can develop in patients treated for a variety of malignancies, it is most common in patients treated for prostate cancer. This study will review the incidence, molecular characteristics, clinical course, and treatment outcomes of rectal adenocarcinoma in patients previously treated with radiation for prostate cancer. For clarity, we will distinguish between rectal cancer not associated with prostate cancer (RCNAPC), rectal cancer in non-irradiated prostate cancer patients (RCNRPC), and rectal cancer in irradiated prostate cancer patients (RCRPC). RARC represents a unique but understudied subset of rectal cancer, and thus requires a more comprehensive investigation in order to improve its treatment and prognosis.

Sarcopenia is Associated With Oncological Prognosis and the Incidence of Secondary Cancer in Patients With Middle/Lower Rectal Cancer

OBJECTIVE

This study evaluated the clinical implications of sarcopenia for patients with rectal cancer according to cancer progression.

SUMMARY BACKGROUND DATA

The negative impact of body composition on long-term outcome has been demonstrated for various malignancies.

METHODS

We retrospectively reviewed 708 patients with rectal cancer who underwent curative resection at our institution between 2003 and 2020. Factors contributing to long-term outcomes and the incidence of secondary cancer (ISC) were analyzed. Psoas muscle mass index (PMI) was assessed using preoperative computed tomography. Sarcopenia was defined using the PMI cut-off values for Asian adults (6.36 cm²/m² for males and 3.92 cm2/m2 for females).

RESULTS

Sarcopenia was identified in 306 patients (43.2%). Sarcopenia was associated with advanced age, low body mass index, smoking history, and advanced T-stage. Multivariate analysis showed sarcopenia was an independent poor prognostic factor for OS (HR 1.71; P = .0102) and cancer-specific survival (HR 1.64; P = .0490). Patients with sarcopenia had significantly higher mortality due to cancer-related death in stages III and IV, whereas non-rectal cancer-related death, including secondary cancer, was markedly increased in stage 0-II sarcopenic rectal patients. Five-year cumulative ISC in patients with and without sarcopenia was 11.8% and 5.9%, respectively. Multivariate analysis revealed that sarcopenia was an independent predictive factor for ISC (HR 2.05; P = .0063).

CONCLUSIONS

Sarcopenia helps predict survival outcomes and cause of death according to cancer stage for patients with middle/lower rectal cancer who underwent radical surgery. Furthermore, sarcopenia increased the development of secondary cancer in those patients.

Risks of second non-breast primaries following breast cancer in women: a systematic review and meta-analysis

BACKGROUND

Second primary cancer incidence is rising among breast cancer survivors. We examined the risks of non-breast second primaries, in combination and at specific cancer sites, through a systematic review and meta-analysis.

METHODS

We conducted a systematic search of PubMed, Embase, and Web of Science, seeking studies published by March 2022. We included studies that reported standardized incidence ratios (SIRs), with associated standard errors, assessing the combined risk of second non-breast primaries following breast cancer. We performed meta-analyses of combined second primary risks, stratifying by age, follow-up duration, and geographic region. We also assessed second primary risks at several specific sites, stratifying by age. The inverse variance method with DerSimonian-Laird estimators was used in all meta-analyses, assuming a random-effects model. Associated biases and study quality were evaluated using the Newcastle-Ottawa scale.

RESULTS

One prospective and twenty-seven retrospective cohort studies were identified. SIRs for second non-breast primaries combined ranged from 0.84 to 1.84. The summary SIR estimate was 1.24 (95% CI 1.14-1.36, I2: 99%). This varied by age: the estimate was 1.59 (95% CI 1.36-1.85) when breast cancer was diagnosed before age 50, which was significantly higher than in women first diagnosed at 50 or over (SIR: 1.13, 95% CI 1.01-1.36, p for difference: < 0.001). SPC risks were also significantly higher when based on Asian, rather than European, registries (Asia-SIR: 1.47, 95% CI 1.29-1.67. Europe-SIR: 1.16, 95% CI 1.04-1.28). There were significantly increased risks of second thyroid (SIR: 1.89, 95% CI 1.49-2.38), corpus uteri (SIR: 1.84, 95% CI 1.53-2.23), ovary (SIR: 1.53, 95% CI 1.35-1.73), kidney (SIR: 1.43, 95% CI 1.17-1.73), oesophagus (SIR: 1.39, 95% CI 1.26-1.55), skin (melanoma) (SIR: 1.34, 95% CI 1.18-1.52), blood (leukaemia) (SIR: 1.30, 95% CI 1.17-1.45), lung (SIR: 1.25, 95% CI 1.03-1.51), stomach (SIR: 1.23, 95% CI 1.12-1.36) and bladder (SIR: 1.15, 95% CI 1.05-1.26) primaries.

CONCLUSIONS

Breast cancer survivors are at significantly increased risk of second primaries at many sites. Risks are higher for those diagnosed with breast cancer before age 50 and in Asian breast cancer survivors compared to European breast cancer survivors. This study is limited by a lack of data on potentially confounding variables. The conclusions may inform clinical management decisions following breast cancer, although specific clinical recommendations lie outside the scope of this review.

Radiotherapy or Surgery of the Axilla After a Positive Sentinel Node in Breast Cancer: 10-Year Results of the Randomized Controlled EORTC 10981-22023 AMAROS Trial

Clinical trials frequently include multiple end points that mature at different times. The initial report, typically based on the primary end point, may be published when key planned co-primary or secondary analyses are not yet available. Clinical Trial Updates provide an opportunity to disseminate additional results from studies, published in JCO or elsewhere, for which the primary end point has already been reported.

PURPOSE

The European Organisation for Research and Treatment of Cancer 10981-22023 AMAROS trial evaluated axillary lymph node dissection (ALND) versus axillary radiotherapy (ART) in patients with cT1-2, node-negative breast cancer and a positive sentinel node (SN) biopsy. At 5 years, both modalities showed excellent and comparable axillary control, with significantly less morbidity after ART. We now report the preplanned 10-year analysis of the axillary recurrence rate (ARR), overall survival (OS), and disease-free survival (DFS), and an updated 5-year analysis of morbidity and quality of life.

METHODS

In this open-label multicenter phase III noninferiority trial, 4,806 patients underwent SN biopsy; 1,425 were node-positive and randomly assigned to either ALND (n = 744) or ART (n = 681).

RESULTS

Per intention-to-treat analysis, 10-year ARR cumulative incidence was 0.93% (95% CI, 0.18 to 1.68; seven events) after ALND and 1.82% (95% CI, 0.74 to 2.94; 11 events) after ART (hazard ratio [HR], 1.71; 95% CI, 0.67 to 4.39). There were no differences in OS (HR, 1.17; 95% CI, 0.89 to 1.52) or DFS (HR, 1.19; 95% CI, 0.97 to 1.46). ALND was associated with a higher lymphedema rate in updated 5-year analyses (24.5% v 11.9%; P < .001). Quality-of-life scales did not differ by treatment through 5 years. Exploratory analysis showed a 10-year cumulative incidence of second primary cancers of 12.1% (95% CI, 9.6 to 14.9) after ART and 8.3% (95% CI, 6.3 to 10.7) after ALND.

CONCLUSION

This 10-year analysis confirms a low ARR after both ART and ALND with no difference in OS, DFS, and locoregional control. Considering less arm morbidity, ART is preferred over ALND for patients with SN-positive cT1-2 breast cancer.

Outcomes and toxicities after proton partial breast radiotherapy for early stage, hormone receptor positive breast cancer: 3-Year results of a phase II multi-center trial

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Proton therapy is a good treatment option for partial breast irradiation.

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Proton PBI results in excellent local tumor control and OAR sparing.

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Cosmesis and quality of life with PBT are comparable to other PBI modalities.

Purpose

Proton therapy (PT) for partial breast irradiation (PBI) in early-stage breast cancer can decrease morbidity versus photon PBI with superior organs-at-risk sparing. We report 3-year outcomes of the first prospective, multicenter, phase II trial of proton PBI.

Methods and Materials

This Proton Collaborative Group phase II trial (PCG BRE007-12) recruited women ≥ 50 years with node-negative, estrogen receptor (ER)-positive, ≤3cm, invasive ductal carcinoma (IDC) or ductal carcinoma in situ undergoing breast conserving surgery followed by proton PBI (40 Gy(RBE), 10 daily fractions). Primary endpoint was freedom from ipsilateral breast cancer recurrence. Adverse events were prospectively graded using CTCAEv4.0. Breast Cancer Treatment Outcome Scale (BCTOS) assessed patient-reported quality of life (PRQOL).

Results

Thirty-eight evaluable patients enrolled between 2/2013–11/2016. Median age was 67 years (range 50–79); 55 % had left-sided disease, and median tumor size was 0.9 cm. Treatment was delivered in ≥ 2 fields predominantly with uniform scanning PT (n = 37). At 35-month median follow-up (12–62), all patients were alive, and none had local, regional or distant disease progression. One patient developed an ER-negative contralateral IDC. Seven grade 2 adverse events occurred; no radiotherapy-related grade ≥ 3 toxicities occurred. Changes in BCTOS subdomain mean scores were maximum 0.36, indicating no meaningful change in PRQOL. Median heart volume receiving 5 Gy (V5Gy), lung V20Gy, and lung V10Gy were 0 %, 0 % and 0.19 %, respectively.

Conclusion

At 3 years, proton PBI provided 100 % cancer control for early-stage, ER-positive breast cancer. Toxicities are minimal, and PRQOL remains acceptable with continued follow-up. These findings support PT as a safe and effective PBI delivery option.

Genetic Risk of Second Primary Cancer in Breast Cancer Survivors: The Multiethnic Cohort Study

Women who have had breast cancer in the past are at increased risk of developing a second primary cancer (SPC), including second primary breast cancer (SPBC) or a second primary non-breast cancer (SPNBC). In the Multiethnic Cohort (MEC) Study, we conducted a prospective cohort analysis in 3,223 female breast cancer survivors from five racial/ethnic populations (White, African American, Japanese American, Latino, and Native Hawaiian) to assess the association of rare pathogenic variants (PV) in 37 known cancer predisposition genes with risk of SPC. A total of 719 (22.3%) women developed SPC, of which, 323 (10.0%) were SPBC. Germline PVs in BRCA1 (HR, 2.28; 95% CI, 1.11-4.65) and ERCC2 (HR, 3.51; 95% CI, 1.29-9.54) were significantly enriched in women with SPC. In the subtype analysis for SPBC, a significant association of ERCC2 PVs (HR, 5.09; 95% CI, 1.58-16.4) and a suggestive association of BRCA2 PVs (HR, 2.24; 95% CI, 0.91-5.55) were observed. There was also a higher risk of SPNBC in carriers of BRCA1 PVs (HR, 2.98; 95% CI, 1.21-7.36). These results provide evidence that germline PVs in BRCA1, BRCA2, and ERCC2 contribute to the development of SPC in breast cancer survivors. These findings also suggest that compromised DNA repair mechanisms could be a predisposition factor for SPC in patients with breast cancer, supporting the need for closer monitoring of SPC in women carrying PVs in these genes.

SIGNIFICANCE

This multiethnic study links germline pathogenic variants in BRCA1, BRCA2, and ERCC2 to the development of second primary cancer in breast cancer survivors, providing biological insights and biomarkers to guide patient monitoring.

Risk of secondary malignancy after radiotherapy for breast cancer: long-term follow-up of Japanese patients with breast cancer

Purpose

There have been very few reports of secondary malignancies after breast cancer treatment in Asia, particularly in Japan. This study aimed to evaluate the risk of secondary malignancies after radiotherapy (RT) in Japanese breast cancer patients.

Methods

This single-center retrospective study included patients who underwent RT between July 1961 and September 2006 for postoperative breast cancer. A total of 702 patients with a follow-up period of more than 5 years were analyzed. All malignancies observed at more than 5 years after the start of RT were defined as secondary malignancies. To calculate the relative risk (RR) of secondary malignancies, we applied data from the National Cancer Center in Japan.

Results

The median observation period was 9.7 (interquartile range 7.1–18.2) years. The cumulative person-years of observation were 6879.4. The RR of contralateral breast cancer increased by 1.85-fold (95% confidence interval [CI] 1.05–3.26) among patients compared with that among the general population; however, the difference was not significant (p = 0.053). The RR of secondary malignancies other than breast cancer increased by 2.71-fold (95% CI 1.99–3.70, p < 0.001) among the patients compared with the general population. Even when only malignancies detected more than 10 years after RT were defined as secondary malignancies, the RR of secondary malignancies other than breast cancer was 1.91 (95% CI 1.33–2.73, p < 0.001).

Conclusion

The incidence of secondary malignancies after RT may be somewhat higher in Japanese patients with breast cancer than in the general population.

Common Multiple Primary Cancers Associated With Breast and Gynecologic Cancers and Their Risk Factors, Pathogenesis, Treatment and Prognosis: A Review

The mammary gland is closely related to the female reproductive system in many aspects, affecting the whole gynecological system. Breast cancer (BC) is the most common malignancy in women and associated with considerable negative effects. Due to various factors including co-pathogenic genetic mutations, environment factors, lifestyle, behavioral factors, treatment regimens and in-creased survival of patients with BC, there is an increased probability of developing additional primary gynecologic cancers such as ovarian cancer (OC), endometrial cancer (EC), and cervical cancer (CC). More and more studies have been conducted in recent years. Multiple primary cancers (MPCs), also known as multiple primary malignancies, refers to two or more different primary cancers in the same patient occurring in the same or different organs or tissues. The pathogenesis of multiple primary cancers is complex and has a negative effect on the prognosis and survival of patients. This review discusses the common types of BC-associated MPCs, namely, BC associated with OC, BC associated with EC and BC associated with CC, as well as risk factors, pathogenesis, treatment, and prognosis of MPCs associated with breast and gynecologic cancers. It provides new intervention and treatment ideas for patients with BC-associated MPCs to improve quality of life and prognosis.

Limited Impact of Breast Cancer and Non-breast Malignancies on Survival in Older Patients with Early-Stage Breast Cancer: Results of a Large, Single-Centre, Population-Based Study

AIMS

To analyse the disease-free survival and overall survival in older adults with breast cancer after breast-conserving therapy, focusing on the relevance of non-breast malignancy (NBM) with respect to survival rates.

MATERIALS AND METHODS

Analyses were based on 1205 women aged 65 years and older with breast cancer treated with breast-conserving therapy between 1999 and 2015. Patients were divided into three age categories: 65-70, 71-75 and >75 years. Multivariate survival analysis was carried out using Cox regression analysis.

RESULTS

The two youngest age categories showed excellent results, with a 12-year disease-free survival of 84.6 and 86.3%, respectively. We noted a 17.2% incidence of NBM, particularly for colon cancer and lung cancer. Most (72.9%) occurred after a diagnosis of breast cancer. Of those 72.9%, about 50% died as a result of NBM within 2 years of the diagnosis of NBM. The overall 12-year NBM-specific survival was 92.0%. The 12-year overall survival was 60.0% for all and for the three abovementioned age categories was 73.3, 54.4 and 28.4%, respectively. The cause of death for all was predominantly non-malignancy-related morbidity.

CONCLUSION

The impact of breast cancer on life expectancy was limited, in particularly for women aged 65-75 years. The relevance of NBM on survival was limited.

Synchronous Hürthle cell and medullary thyroid carcinomas

Hürthle cell carcinoma (HCC) and medullary thyroid carcinomas (MTC) are uncommon histological subtypes of thyroid cancers, each accounting for around 3% of all thyroid cancers. A septuagenarian woman with a history of multiple primary cancer diagnoses presented with a growing left-sided neck lump. A diagnostic left thyroid lobectomy was performed, and pathological examination found two separate malignant foci: one HCC and an MTC. The patient developed left-sided HCC nodal metastasis, and following several multidisciplinary team discussions, a right completion lobectomy with left lateral neck dissection was performed, revealing further intrathyroidal MTC and extranodal extension of HCC. We present this as the first reported case of a collision tumour of HCC and MTC, and review the available literature regarding collision tumours and their management.

Estimation of secondary cancer projected risk after partial breast irradiation at the 1.5 T MR-linac

PURPOSE

For patients treated with partial breast irradiation (PBI), potential long-term treatment-related toxicities are important. The 1.5 T magnetic resonance guided linear accelerator (MRL) offers excellent tumor bed visualization and a daily treatment plan adaption possibility, but MRL-specific electron stream and return effects may cause increased dose deposition at air-tissue interfaces. In this study, we aimed to investigate the projected risk of radiation-induced secondary malignancies (RISM) in patients treated with PBI at the 1.5 T MRL.

METHODS

Projected excess absolute risk values (EARs) for the contralateral breast, lungs, thyroid and esophagus were estimated for 11 patients treated with PBI at the MRL and compared to 11 patients treated with PBI and 11 patients treated with whole breast irradiation (WBI) at the conventional linac (CTL). All patients received 40.05 Gy in 15 fractions. For patients treated at the CTL, additional dose due to daily cone beam computed tomography (CBCT) was simulated. The t‑test with Bonferroni correction was used for comparison.

RESULTS

The highest projected risk for a radiation-induced secondary cancer was found for the ipsilateral lung, without significant differences between the groups. A lower contralateral breast EAR was found for MRL-PBI (EAR = 0.89) compared to CTL-PBI (EAR = 1.41, p = 0.01), whereas a lower thyroid EAR for CTL-PBI (EAR = 0.17) compared to MRL-PBI (EAR = 0.33, p = 0.03) and CTL-WBI (EAR = 0.46, p = 0.002) was observed. Nevertheless, when adding the CBCT dose no difference between thyroid EAR for CTL-PBI compared to MRL-PBI was detected.

CONCLUSION

Better breast tissue visualization and the possibility for daily plan adaption make PBI at the 1.5 T MRL particularly attractive. Our simulations suggest that this treatment can be performed without additional projected risk of RISM.

Fluence map analyzer reduces low dose volume in locally advanced post mastectomy breast cancer patients

Multi-leaf collimator dose leakage in intensity-modulated radiotherapy (IMRT) plans causes higher low dose volume which increases the long-term risks of radiotherapy. We have developed Fluence Map Analyzer (FMA) program that suggests the ideal field geometry to reduce low dose volume in locally advanced breast cancer IMRT plans. In this comparative experimental study, FMA has been applied to standard IMRT plans (STD-IMRT) of randomly selected 15 left and 15 right-sided locally advanced breast cancer patients. All patients underwent a modified radical mastectomy. The chest wall, IMN, axillary, and supraclavicular lymph nodes are included in planning target volume (PTV). The heart, lungs, contralateral breast, and medulla spinalis were delineated as organs at risk (OARs). Two sets of plans, namely STD-IMRT and FMA-IMRT, were generated for each patient. The dosimetric analysis was performed using dose-volume histogram (DVH) and standard evaluation parameters of PTV and OARs. No differences could be observed among the two techniques for PTV coverage. However, FMA-IMRT plans achieved significantly lower V5volumes and mean doses of the heart, lungs, contralateral breast, and body contours. FMA-IMRT used a smaller number of sub-fields and fewer monitor units (MU). FMA automizes the field geometry determination process for locally advanced breast cancer IMRT planning while reducing low dose volume significantly.

Multimodal treatment of radiation-induced esophageal cancer: Results of a case-matched comparative study from a single center

PURPOSE

Radiation-induced esophageal cancer (RIEC) is a rare but severe late consequence of radiotherapy. The literature regarding this topic is predominately limited in describing the risk of this disease. Tumor behavior, treatment strategies, and prognosis of this cancer remain poorly defined.

PATIENTS AND METHODS

We collected data of patients who were referred to our unit between 2000 and 2020 for RIEC. After tumor board discussion, upfront surgery or neoadjuvant therapy and surgery were indicated as the main treatment. Preoperative characteristics, long-term and short-term postoperative outcomes of RIEC patients were compared with a 1:1 clustering-matched cohort of patients affected by primary esophageal cancer (PEC).

RESULTS

At pre-matching, 54 RIEC and 936 PEC patients were enrolled. The median time between primary irradiation and diagnosis of RIEC was 13.5 years, and the median primary radiation dose was 60 Gy. Compared to the unmatched cohort of PECs, RIEC patients were more frequently female (p = 0.0007), had earlier detection of disease (p = 0.03) and presented more frequently with upper esophageal cancers (p < 0.0001). Neoadjuvant treatment was used less frequently in RIEC patients (p < 0.0001). After matching, the 51 RIEC and 50 PEC patients showed comparable results in terms of exposure to neoadjuvant treatment, surgical radicality and survival outcomes. RIEC patients had more severe postoperative complications (p = 0.04) and a higher proportion of pulmonary complications (p = 0.04).

CONCLUSIONS

Curative treatments are feasible for RIEC. Neoadjuvant chemotherapy or chemoradiation can be used in this subgroup, treatment response and long-term outcomes are comparable to those of PEC. The risk of postoperative complications is probably related to the detrimental effect of primary irradiation on lung function.

Risk of Second Primary Thyroid Cancer in Women with Breast Cancer

Simple Summary

The goal of this study was to estimate the risk of thyroid cancer following a diagnosis of breast cancer and to identify (therapeutic and genetic) risk factors for the development of thyroid cancer after breast cancer. We followed 10,832 breast cancer patients for a mean of 14 years for new cases of thyroid cancer. Of the 10,832 women with breast cancer, 53 (0.49%) developed a second case of primary thyroid cancer. The ten-year risk of thyroid cancer was higher in women who carried a CHEK2 mutation (1.5%) than in women who carried no mutation (0.9%). In Poland, following a diagnosis of breast cancer, the risk of thyroid cancer is increased four times, but is increased nine times in women who carry a CHEK2 mutation.

Abstract

The goal of this study was to estimate the risk of thyroid cancer following breast cancer and to identify therapeutic and genetic risk factors for the development of thyroid cancer after breast cancer. We followed 10,832 breast cancer patients for a mean of 14 years for new cases of thyroid cancer. All women were genotyped for three Polish founder mutations in BRCA1 (C61G, 4153delA, 5382insC) and four mutations in CHEK2 (1100delC, IVS2 + 1G/A, del5395, I157T). Information was collected on chemotherapy, radiotherapy, hormonal therapies, and oophorectomy. Of the 10,832 women, 53 (0.49%) developed a second primary thyroid cancer. Based on Polish population statistics, the expected number was 12.4 (SIR = 4.3). The ten-year risk of developing thyroid cancer was higher in women who carried a CHEK2 mutation (1.5%) than in women who carried no mutation (0.9%). The age-adjusted hazard ratio for developing thyroid cancer was 1.89 (0.46–7.79; p = 0.38) for those with a CHEK2 protein-truncating mutation and 2.75 (1.29–5.85; p = 0.009) for those with a CHEK2 missense mutation.

Association between Thyroid Cancer and Breast Cancer: Two Longitudinal Follow-Up Studies Using a National Health Screening Cohort

Background: The purpose of this study was to evaluate the association between thyroid cancer and breast cancer. Methods: Data from the Korean National Health Insurance Service-Health Screening Cohort were collected from 2002 to 2013. In study I, 3949 thyroid cancer participants were 1:4 matched with 15,796 control I participants, and hazard ratios (HRs) with 95% confidence intervals (CIs) for breast cancer were evaluated using a stratified Cox proportional hazard model. In study II, 3308 breast cancer participants were 1:4 matched with 13,232 control II participants, and HRs with 95% CIs for thyroid cancer were assessed in the same way as in study I. In the subgroup analyses, associations were analyzed according to radioactive iodine (RAI) treatment and age (<60 years old and ≥60 years old). Results: The adjusted HR for breast cancer in the thyroid cancer group was 1.64 (95% CI = 1.13–2.39, p = 0.010). The adjusted HR for thyroid cancer in the breast cancer group was 1.91 (95% CI = 1.47–2.49, p < 0.001). In the subgroup analyses, the groups that were older and not treated with RAI treatment showed consistent results in study I, and the younger and older groups showed consistent results in study II. Conclusions: Based on this cohort study, breast and thyroid cancer have a reciprocal positive association.

Radiation-induced tumors and secondary malignancies following radiotherapy

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Toxicity of Hypofractionated Whole Breast Radiotherapy Without Boost and Timescale of Late Skin Responses in a Large Cohort of Early-Stage Breast Cancer Patients

AIM

To report toxicity of hypofractionated whole-breast radiotherapy in a large cohort of early-stage breast cancer (BCaients.

MATERIALS AND METHODS

From 02/2009-05/2017, 1325 consecutive BCa patients were treated with 40.05 Gy/15 fractions, without boost. Median age was 62 (IQR:51.1-70.5) years. Chemotherapy was prescribed for 28% of patients, hormonal therapy for 80.3%, monoclonal antibodies for 8.2%.

RESULTS

Median follow-up was 72.4 (IQR: 44.6-104.1) months. Acute RTOG toxicity was: 69.8% Grade (G) 1, 14.3% G2 and 1.7% G3. Late SOMA-LENT toxicities were: edema-hyperpigmentation (E-H): G1 28.67%, G2 4.41%, G3 0.15%; fibrosis-atrophy-telangiectasia-pain (F-A-T-P): G1 14.6%, G2 3.2%, G3 0.8%, G4 0.1%. Median time to first occurrence was 6 and 18 months, respectively. Aesthetic result after surgery was excellent in 28.7%, good in 41.5%, acceptable in 20.3% and poor in 9.5% of patients. Change in breast appearance after radiotherapy was mild in 6.9%, moderate in 2.3% and marked in 1.3% of patients. Concomitant chemotherapy, obesity, smoking, use of bolus and planning target volume (PTV) were associated with higher acute toxicity. Patients ≥55 years old were less likely to experience acute toxicity. PTV and acute G2 toxicity were associated with ≥G2 E-H. PTV, concomitant chemotherapy, hypertension and ≥G2 acute toxicity were associated with increased risk of F-A-T-P.

CONCLUSION

Hypofractionated whole-breast radiotherapy without boost demonstrated mild acute and late toxicity in a large cohort of consecutive patients. Moderate and marked changes in breast appearance were registered for 3.6% of patients and occurred between 18 to 42 months.

TGF-β1-stimulation of NFATC2 and ATF3 proteins and their interaction for matrix metalloproteinase 13 expression in human breast cancer cells

Activating transcription factor 3 (ATF3), an inducible stress gene, is stimulated by transforming growth factor-beta1 (TGF-β1) in a protracted and relentless manner in human mammary cancer cells (hBC cells; MDA-MB231). The molecular mechanism behind this stable expression of ATF3 via TGF-β1 in MDA-MB231 cells is unknown. This study found that TGF-β1 stimulated the expression of the nuclear factor of activated T Cells 2 (NFATC2) in MDA-MB231 cells and provided evidence of its interaction with ATF3. The functional characterization of NFATC2 in association with ATF3 was determined by silencing of NFATC2 using siRNA. Knock-down of NFATC2 decreased the expression of both ATF3 and its target gene MMP13 (matrix metalloproteinase 13, a critical invasive gene) in hBC cells. Chromatin immunoprecipitation revealed that TGF-β1 promoted NFATC2 binding and NFATC2-ATF3 complex binding at the MMP13 promoter region, whereas silencing of NFATC2 decreased their binding in hBC cells. Thus, we uncovered the mechanism of interaction between NFATC2 and ATF3 regulated by TGF-β1, and NFATC2 acted as a pivotal factor in providing ATF3 stability and further drove MMP13 transcription. Targeting NFATC2 and blocking its association with ATF3 could therefore help to slow the progression of breast cancer.

3D Breast Tumor Models for Radiobiology Applications

Breast cancer is a leading cause of cancer-associated death in women. The clinical management of breast cancers is normally carried out using a combination of chemotherapy, surgery and radiation therapy. The majority of research investigating breast cancer therapy until now has mainly utilized two-dimensional (2D) in vitro cultures or murine models of disease. However, there has been significant uptake of three-dimensional (3D) in vitro models by cancer researchers over the past decade, highlighting a complimentary model for studies of radiotherapy, especially in conjunction with chemotherapy. In this review, we underline the effects of radiation therapy on normal and malignant breast cells and tissues, and explore the emerging opportunities that pre-clinical 3D models offer in improving our understanding of this treatment modality.

Exposure of the oesophagus in breast cancer radiotherapy: A systematic review of oesophagus doses published 2010-2020

BACKGROUND AND PURPOSE

Breast cancer radiotherapy can increase the risk of subsequent primary oesophageal cancer, with risk increasing according to oesophagus radiation dose. We describe oesophagus exposure from modern breast cancer regimens and discuss the risks of oesophageal cancer for women irradiated recently.

MATERIALS AND METHODS

A systematic review was undertaken of oesophagus doses from breast cancer radiotherapy regimens published during 2010-2020. Mean and maximum oesophagus doses were described for different target regions irradiated and different radiotherapy techniques.

RESULTS

In 112 published regimens from 18 countries, oesophagus doses varied with target region. For partial breast irradiation, average mean oesophagus dose was 0.2 Gy (range 0.1-0.4) in four regimens; maximum dose was not reported. For breast or chest wall radiotherapy, average oesophagus doses were mean 1.8 Gy (range 0.1-10.4) in 24 regimens and maximum 6.7 Gy (range 0.4-14.3) in seven regimens. For radiotherapy including a nodal region, average oesophagus doses were higher: mean 11.4 Gy (range <0.1-29.3) in 61 regimens and maximum 34.4 Gy (range 3.4-51.3) in 55 regimens. Average mean oesophagus doses were >10 Gy for intensity modulated nodal radiotherapy, but lower for other node techniques.

CONCLUSIONS

Mean oesophagus doses from partial breast and breast/chest wall regimens were usually less than 2 Gy, hence radiation-risks will be very small. However, for radiotherapy including lymph nodes, average mean oesophagus dose of 11.4 Gy may nearly double oesophageal cancer risk. Consideration of oesophageal exposure during nodal radiotherapy planning may reduce the risks of radiation-related oesophageal cancer for women irradiated today.

Unintended dose to the lower axilla in adjuvant radiotherapy for breast cancer: Differences between tangential beam and VMAT

BACKGROUND AND PURPOSE

To evaluate dosimetric differences in unintended dose to the lower axilla between 3D-standard (3DCRT), tangential beam forward intensity modulated radiotherapy (F-IMRT) and volumetric modulated arc therapy (VMAT). The objective is to evaluate whether results of clinical trials, such as the ACOSOG-Z011 trial, that evaluated omission of axillary clearance can be extrapolated towards more conformal techniques like VMAT.

MATERIALS AND METHODS

Twenty-five consecutive patients treated with whole breast radiotherapy alone (WBRT) using a F-IMRT technique were identified. Three additional plans were created for every patient: one plan using a single 270° arc (VMAT 1x270°), another using two small ≤90° opposing arcs (VMAT 2x < 90°) and thirdly a 3DCRT plan without F-IMRT. Axillary levels I-II were contoured after the treatment plans were made.

RESULTS

The volume of the axilla level I that was covered by the 50% isodose (V50%) was significantly higher for VMAT 2x < 90° (71.3 cm³, 84% of structure volume, p < 0.001) and VMAT 1x270° (68.8 cm³, 81%, p < 0.01) compared to 3DCRT (60.3 cm³, 71%) and F-IMRT (60.8 cm³, 72%). The V50% to the axilla level II, however, was low for all techniques: 12.3 cm³ (12%); 8.9 cm³ (9%); 4.3 cm³ (4%); 4.4 cm³ (4%) for VMAT 2x < 90°, VMAT 1x270°, 3DCRT, F-IMRT, respectively. For the higher doses (V90% and above), no clinically relevant differences were seen between the different modalities.

CONCLUSION

WBRT treatments with VMAT do not lead to a significant reduction of the unintended axillary dose in comparison with a tangential beam setup. Hence, concerning tumor control, VMAT can be applied to clinical situations similar to the Z0011 trial. The intermediate axillary dose is higher with VMAT, but the clinical consequence of this difference on toxicity is unknown.

Previous Extrapulmonary Malignancies Impact Outcomes in Patients With Surgically Resected Lung Cancer

Background: As the overall survival of patients with cancer continues to improve, the incidence of second primary malignancies seems to be increasing. Previous studies have shown controversial results regarding the survival of patients with primary lung cancer with previous extrapulmonary malignancies. This study aimed to determine the clinical picture and outcomes of this particular subgroup of patients. Materials and Methods: We included 2,408 patients who underwent pulmonary resection for primary lung cancer at our institute between January 1, 2011 and December 30, 2017 in this retrospective study. Medical records were extracted and clinicopathological parameters and postoperative prognoses were compared between patients with lung cancer with and without previous extrapulmonary malignancies. Results: There were 200 (8.3%) patients with previous extrapulmonary malignancies. Breast cancer (30.5%), gastrointestinal cancer (17%), and thyroid cancer (9%) were the most common previous extrapulmonary malignancies. Age, sex, a family history of lung cancer, and preoperative carcinoembryonic antigen levels were significantly different between the two groups. Patients with previous breast or thyroid cancer had significantly better overall survival than those without previous malignancies. Conversely, patients with other previous extrapulmonary malignancies had significantly poorer overall survival (p < 0.001). The interval between the two cancer diagnoses did not significantly correlate with clinical outcome. Conclusion: Although overall survival was lower in patients with previous extrapulmonary malignancies, previous breast or thyroid cancer did not increase mortality. Our findings may help surgeons to predict prognosis in this subgroup of patients with primary lung cancer.

Dosimetry and outcomes in patients receiving radiotherapy for synchronous bilateral breast cancers

BACKGROUND

Synchronous bilateral breast cancer (SBBC) is rare and there is little evidence describing organs at risk (OAR) and limits to the heart and lungs caused by radiotherapy (RT). Quantifying mean heart dose (MHD) and mean lung dose (MLD) from RT in this patient cohort may lead to better understanding of doses to OAR and resultant effects on clinical outcomes. The primary objective was to assess median MHD and MLD in SBBC, while secondary aims included analyses of 1) factors associated with MHD and MLD, 2) V5 and V20 values and 3) factors associated with clinical outcomes.

METHODS

Patients planned for adjuvant bilateral whole breast/chest wall (WB) RT from a single institution treated in 2011-2018 were included. Median MHD and MLD (Gy) were stratified by hypofractionated (42.56 Gy/16 fractions, HFRT) and conventional fractionation (50 Gy/ 25 fractions, CFRT) and summarized separately based on the following treatments: 1) locoregional RT, WB tangential RT either 2) no boost 3) sequential boost or 4) simultaneous integrated boost. MHD, MLD, lung V5 and V20 values, and demographics were collected. Linear regression analyses identified factors associated with MHD and MLD and factors associated with clinical outcomes.

RESULTS

A total of 88 patients were included. The median MHD for HFRT and CFRT was 1.99 Gy and 2.94 Gy, respectively. The median MLD for HFRT and CFRT was 6.00 Gy and 10.08 Gy, respectively. MHD and MLD were significantly associated with the occurrence of a cardiac or pulmonary event post-radiation. Patients who had a mastectomy or tumoral muscle involvement were more likely to develop a local recurrence, metastasis or new primary while patients who had a lumpectomy or tumor with a positive estrogen receptor status were less likely to experience these events.

CONCLUSIONS

Further investigation should be conducted to identify SBBC RT techniques that mitigate dose to OARs to improve clinical outcomes in bilateral breast patients.

Contralateral risk-reducing local therapy in breast cancer patients with BRCA1/2 mutations: systemic review and meta-analysis

BACKGROUND

Unilateral breast cancer (UBC) patients with germline pathogenic BRCA1/2 variants have a higher risk of developing contralateral breast cancer (CBC) and need contralateral risk-reducing local treatments, including contralateral risk-reducing mastectomy (CRRM) and prophylactic irradiation (CPI). The aim of our study was to systematically explore the efficacy of CRRM and CPI in reducing CBC risk and increasing survival.

METHODS

A search was done, and eligible randomized trials and cohort studies should include and compare UBC patients with germline pathogenic BRCA1/2 variants who have and have not received contralateral risk-reducing local treatment. Random-effects meta-analysis was used in this study. Primary outcomes of the studies included overall survival (OS) and the incidence of contralateral breast cancer (CBC), and secondary outcomes included breast cancer-specific survival (BCSS).

RESULTS

A total of five studies with 1769 UBC patients with germline pathogenic BRCA1/2 variants were enrolled in our meta-analysis. CRRM was correlated with a lower risk of CBC in UBC patients with germline pathogenic BRCA1/2 variants (summary RR = 0.07; 95%CI 0.03-0.13, I2 = 3%), a significantly increased OS (summary RR, 1.15; 95%CI 1.04-1.26, I2 = 26%) and a significantly increased BCSS (summary RR, 1.18; 95%CI 1.07-1.31, I2 = 64%) compared with surveillance. CPI also decreased the risk of CBC (RR 0.02; 95%CI 0.05-0.88) but did not significantly improve OS (RR 0.97; 95%CI 0.90-1.05) and BCSS (RR 0.97; 95%CI 0.90-1.05) compared with surveillance.

CONCLUSIONS

CRRM reduces CBC risk and increases OS and BCSS in UBC patients with germline pathogenic BRCA1/2 variants, and could be offered as a risk-reducing local treatment. For those who oppose CRRM, CPI could be offered for CBC-risk reduction, while its survival benefit is still uncertain.

A study of the efficacy and tolerability of capecitabine and lobaplatin in advanced HER-2 negative breast cancer patients

Background

This study sought to examine the efficacy and adverse reactions of capecitabine and lobaplatin in the treatment of metastatic human epidermal growth factor receptor 2 (HER-2) negative breast cancer (BC).

Methods

This retrospective study examined 45 patients diagnosed with advanced HER-2 negative BC. Patients were enrolled in this study from November 2015 to June 2019. The patients received capecitabine and lobaplatin combination therapy. The therapeutic efficacy and side effects were evaluated after at least 2 cycles of treatment.

Results

Therapeutic efficacy and adverse reactions were evaluated in 38 patients, comprising 12 cases of partial response (PR), 19 cases of stable disease (SD), and 7 cases of progressive disease (PD). Among these, 3 patients required treatment delays or dose reductions for subsequent cycles, and 2 patients discontinued treatment. The overall response rate (ORR) was 31.58% and the disease control rate (DCR) was 81.58%. The ORR and DCR for hormone receptor positive, HER-2 negative (HR+/HER-2−) and triple negative breast cancer (TNBC) patients were 31.82% and 31.25%, and 86.36% and 75%, respectively. The median progression free survival (PFS) was 8 months, 6 months, and 6 months in patients receiving the therapeutics as a first-line, second-line, or third-line and beyond treatment, respectively. The main side effects were myelosuppression, including granulocytopenia, thrombocytopenia, and anemia. Among patients with grade 1 side effects or above, 28 patients (73.68%) had myelosuppression, and 13 patients (34.21%) had gastrointestinal reactions. Further, we investigated the association between side effects and clinical outcomes, and found that PFS was increased in patients with myelosuppression and gastrointestinal reactions.

Conclusions

Capecitabine and lobaplatin combination therapy was effective and well tolerated among patients with advanced HER-2 negative BC.

Comparison of volumetric modulated arc therapy and intensity-modulated radiotherapy for left-sided whole-breast irradiation using automated planning

Background

Published treatment technique comparisons for postoperative left-sided whole breast irradiation (WBI) with deep-inspiration breath-hold (DIBH) are scarce, small, and inconclusive. In this study, fully automated multi-criterial plan optimization, generating a single high-quality, Pareto-optimal plan per patient and treatment technique, was used to compare for a large patient cohort 1) intensity modulated radiotherapy (IMRT) with two tangential fields and 2) volumetric modulated arc therapy (VMAT) with two small tangential subarcs.

Materials and methods

Forty-eight randomly selected patients recently treated with DIBH and 16 × 2.66 Gy were included. The optimizer was configured for the clinical planning protocol. Comparisons between IMRT and VMAT included dosimetric plan parameters, estimated excess relative risks (ERR) for toxicities, delivery times, MUs, and deliverability accuracy at a linac.

Results

The automatically generated IMRT and VMAT plans applied in this study were similar or higher in quality than the manually generated clinical plans. For equal PTVin V95% (98.4 ± 0.9%), VMAT had significant advantages compared to IMRT regarding breast dose homogeneity and doses in heart and ipsilateral lung, at the cost of some minor deteriorations for contralateral breast (few cases with larger deteriorations) and lung. Conformality improved from 1.38 to 1.18 (p < 0.001). With VMAT, ERR for major coronary events and ipsilateral lung tumors were reduced by 3% (range: −1–12%) and 16% (range: −3–38%), respectively. MUs and delivery times were higher for VMAT. There were no statistical differences in γ passing rates.

Conclusion

For WBI in conservative therapy of left-sided breast patients treated with DIBH, VMAT with two tangential subarcs was generally dosimetrically superior to IMRT with two tangential static fields. Results need confirmation by robustness analyses.

Postmastectomy radiotherapy for all node positive patients: The case against

Postmastectomy radiotherapy (PMRT) is accepted as the standard of care for women with early breast cancer with 4 or more involved axillary nodes. However the role of PMRT in women with 1-3 involved nodes remains controversial and guidelines vary. We present the arguments against advocating postmastectomy radiotherapy for all women with node positive breast cancer.

Risks of subsequent primary cancers among breast cancer survivors according to hormone receptor status

BACKGROUND

This study was aimed at examining the risks of subsequent primary cancers (SPCs) among breast cancer survivors by hormone receptor (HR) status and age at diagnosis.

METHODS

Data from 12 Surveillance, Epidemiology, and End Results registries were used to identify 431,222 breast cancer survivors (at least 1 year) diagnosed between the ages of 20 and 84 years from 1992 to 2015. Risks of SPCs were measured as the standardized incidence ratio (SIR) and the excess absolute risk (EAR) per 10,000 person-years. Poisson regression was used to test the difference in SIRs by HR status.

RESULTS

In comparison with the general population, the risk of new cancer diagnoses among survivors was 20% higher for those with HR-positive cancers (SIR, 1.20; 95% confidence interval [CI], 1.19-1.21; EAR, 23.3/10,000 person-years) and 44% higher for those with HR-negative cancers (SIR, 1.44; 95% CI, 1.41-1.47; EAR, 45.2/10,000 person-years), with the risk difference between HR statuses statistically significant. The higher risk after HR-negative cancer was driven by acute nonlymphocytic leukemia and breast, ovarian, peritoneal, and lung cancers. By age at diagnosis, the total EAR per 10,000 person-years ranged from 15.8 (95% CI, 14.1-17.5; SIR, 1.11) among late-onset (age, 50-84 years) HR-positive survivors to 69.4 (95% CI, 65.1-73.7; SIR, 2.24) among early-onset (age, 20-49 years) HR-negative survivors, with subsequent breast cancer representing 73% to 80% of the total EAR. After breast cancer, the greatest EARs were for ovarian cancer among early-onset HR-negative survivors, lung cancer among early- and late-onset HR-negative survivors, and uterine corpus cancer among late-onset HR-positive survivors.

CONCLUSIONS

Risks of SPCs after breast cancer differ substantially by subtype and age. This suggests that more targeted approaches for cancer prevention and early-detection strategies are needed in survivorship care planning.

Regulation of bone metastasis and metastasis suppressors by non-coding RNAs in breast cancer

Breast cancer (BC) is a critical health care issue that substantially affects women worldwide. Though surgery and chemotherapy can effectively control tumor growth, metastasis remains a primary concern. Metastatic BC cells predominantly colonize in bone, owing to their rigid osseous nutrient-rich nature. There are recently increasing studies investigating the context-dependent roles of non-coding RNAs (ncRNAs) in metastasis regulation. ncRNAs, including microRNAs, long non-coding RNAs, circular RNAs, and small interference RNAs, control the BC metastasis via altered mechanisms. Additionally, these ncRNAs have been reported in regulating a unique class of genes known as Metastatic suppressors. Metastasis suppressors like BRMS1, NM23, LIFR, and KAI1, etc., have been extensively studied for their role in inducing apoptosis, inhibiting metastasis, and maintaining homeostasis. In this review, we have emphasized the direct regulation of ncRNAs for effectively controlling the distant spread of BC. Furthermore, we have highlighted the ncRNA-mediated modulation of the metastatic suppressors, thereby delineating their indirect influence over metastasis.

Single-dose intraoperative radiotherapy during lumpectomy for breast cancer: an innovative patient-centred treatment

In the randomised TARGIT-A trial, risk-adapted targeted intraoperative radiotherapy (TARGIT-IORT) during lumpectomy was non-inferior to whole-breast external beam radiotherapy, for local recurrence. In the long-term, no difference was found in any breast cancer outcome, whereas there were fewer deaths from non-breast-cancer causes. TARGIT-IORT should be included in pre-operative consultations with eligible patients.

Atlas of sentinel lymph nodes in early breast cancer using single-photon emission computed tomography: implication for lymphatic contouring

PURPOSE

to determine the localization of sentinel lymph nodes (SLNs) in a large cohort of patients with breast cancer and validate the European Society for Therapeutic Radiology and Oncology (ESTRO), Radiation Therapy Oncology Group (RTOG), and Radiotherapy Comparative Effectiveness (RADCOMP) guidelines on regional lymph node clinical target volume (CTV-LN) delineation.

MATERIALS AND METHODS

A total of 254 women with cT1-3N0-1M0 breast cancer underwent single-photon emission computed tomography (SPECT-CT) visualization of SLNs after intra- and peritumoral injection of 99mTc-radiocolloids. All SPECT-CT images were fused with reference simulation computed tomography. A 3D atlas of SLNs was created and used for evaluation of CTV-LN defined by contouring guidelines.

RESULTS

SPECT-CT visualized 532 SLNs that were localized in axillary level I in 67.5%, level II in 15.4%, level III in 7.3%, internal mammary in 8.5%, and supraclavicular in 1.3% cases. The majority of level II-IV and internal mammary SLNs were inside the recommended CTV-LN. Axillary level I SLNs were covered by ESTRO and RTOG contours in 85% and 85% cases, respectively. "Out of contours" SLNs were mostly detected in lateral subgroup of level I LN (18.5%), while 98%-99% of anterior pectoral and central axillary SLNs were covered by CTV-LN. Internal mammary SLNs were visualized in 33 cases and were outside ESTRO and RTOG contours in 3 and 6 observations, respectively.

CONCLUSION

SPECT-CT atlas of SLNs demonstrated that in most cases ESTRO and RTOG guidelines correctly represented CTV-LNs with the exception of lateral subgroup of SLNs.

Multicatheter interstitial brachytherapy versus stereotactic radiotherapy with CyberKnife for accelerated partial breast irradiation: a comparative treatment planning study with respect to dosimetry of organs at risk

Background

The aim of the study was to dosimetrically compare multicatheter interstitial brachytherapy (MIBT) and stereotactic radiotherapy with CyberKnife (CK) for accelerated partial breast irradiation (APBI) especially concerning the dose of organs at risk (OAR-s).

Patients and methods

Treatment plans of thirty-two MIBT and CK patients were compared. The OAR-s included ipsilateral non-target and contralateral breast, ipsilateral and contralateral lung, skin, ribs, and heart for left-sided cases. The fractionation was identical (4 x 6.25 Gy) in both treatment groups. The relative volumes (e.g. V100, V90) receiving a given relative dose (100%, 90%), and the relative doses (e.g. D0.1cm³, D1cm³) delivered to the most exposed small volumes (0.1 cm³, 1 cm³) were calculated from dose-volume histograms. All dose values were related to the prescribed dose (25 Gy).

Results

Regarding non-target breast CK performed slightly better than MIBT (V100: 0.7% vs. 1.6%, V50: 10.5% vs. 12.9%). The mean dose of the ipsilateral lung was the same for both techniques (4.9%), but doses irradiated to volume of 1 cm³ were lower with MIBT (36.1% vs. 45.4%). Protection of skin and rib was better with MIBT. There were no significant differences between the dose-volume parameters of the heart, but with MIBT, slightly larger volumes were irradiated by 5% dose (V5: 29.9% vs. 21.2%). Contralateral breast and lung received a somewhat higher dose with MIBT (D1cm³: 2.6% vs. 1.8% and 3.6% vs. 2.5%).

Conclusions

The target volume can be properly irradiated by both techniques with similar dose distributions and high dose conformity. Regarding the dose to the non-target breast, heart, and contralateral organs the CK was superior, but the nearby organs (skin, ribs, ipsilateral lung) received less dose with MIBT. The observed dosimetric differences were small but significant in a few parameters at the examined patient number. More studies are needed to explore whether these dosimetric findings have clinical significance.