Breast Irradiation Research Articles

Abstract PO1-22-04: Cosmetic results of the breast in patients treated with Five Fraction Accelerated Partial Breast Irradiation for early stage breast cancer: retrospective review comparing Daily versus Every Other Day Treatment

Abstract Introduction: Breast cosmesis results using Accelerated Partial Breast Irradiation (APBI) with IMRT external beam in 5 fractions (6Gy x 5 fractions) has been reported as good to excellent in the literature. This retrospective review compares breast cosmesis in patients treated with Daily versus Every Other Day APBI in the community practice setting. Methods: The patient electronic medical records (EMR) were used to identify APBI patients treated at the community cancer center with the 6Gy x 5 fraction regimen. Harvard breast cosmesis four point scale results (poor, fair, good, excellent results) were extracted for each treated APBI patient from clinical notes in the EMR to rate breast cosmesis. For many patients in this review, provider reporting of cosmesis in the EMR overlapped good and excellent categories and so a “good to excellent” score was assigned. Therefore, a three point scale was utilized in statistical analysis (poor-1, fair-2, good to excellent-3). Results: There were 62 patients treated with APBI at a single institution with greater than 6 months follow up (18 patients treated daily and 44 patients treated every other day). Median follow up was 12 months (range 6- 32 months). Of all patients treated there were 0 with poor cosmesis, 3 with fair (1 every other day treatment, 2 every day treatment), 59 with good to excellent cosmesis. Univariate logistical regression analysis revealed no significant difference between daily and every other day treatment (p=0.457) Conclusion: With careful patient selection, quality planning and treatment delivery, good to excellent cosmesis is achievable in the great majority of patients undergoing breast APBI (6Gy x 5 fractions) using IMRT in the community radiation oncology clinic with either daily or every other day treatment. More study is needed, but in this review cosmetic differences seem to be minimal between daily and every other day treatment schedules. Citation Format: Alex Goss, Ellaine Haroz, Anna Voltura, Jennifer McGrath, Olivia Sloan, Matthew Jackson, Savvas Morris, Bryan Goss. Cosmetic results of the breast in patients treated with Five Fraction Accelerated Partial Breast Irradiation for early stage breast cancer: retrospective review comparing Daily versus Every Other Day Treatment [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO1-22-04.

Abstract PO5-22-04: Genomic analysis of local recurrences following risk adapted breast radiotherapy in the IMPORT trials defines 'true recurrences' and 'new primaries'

Abstract Background: Most ipsilateral breast tumor recurrences (IBTR) following breast conserving surgery occur near the tumor bed (Veronisi et al, Ann Oncol 2001) and are considered to represent ‘true recurrence’ (derived from residual malignant cells of the index cancer). A smaller number occur elsewhere in the breast and are thought to be ‘new primaries’ (independently occurring cancer). The IMPORT LOW (Coles et al, The Lancet 2017) and IMPORT HIGH (Coles et al, The Lancet 2023) trials investigated adaptation of radiotherapy dose-volume to this spatially varying risk, testing partial breast irradiation and simultaneous integrated boost in patients with tumors at low and high risk of IBTR respectively. We analysed genomic relationships between index cancers and recurrences in these trials, to ascertain the frequency of true recurrences and unrelated new primaries, and their spatial distribution. Methodology: FFPE blocks were obtained from 137 patients who developed subsequent ipsi- or contralateral breast cancer: 66 from IMPORT HIGH and 71 from IMPORT LOW (4 with bilateral second cancers). DNA extracted from index and subsequent cancers underwent shallow whole genome sequencing (sWGS) using the Illumina NovaSeq 6000 system. Copy number profiles were derived from sWGS data using the R package QDNAseq(Scheinin et al, Genome Res 2014); those that failed QC criteria were removed. Relatedness of tumor pairs was determined using the R package Breakclone (Lips et al, Nat Genet 2022). This approach uses individual copy number aberration breakpoint position rather than events at chromosomal arm level. The p value cutoff for relatedness was 0.01; values between 0.01 and 0.05 were considered ambiguous. Researchers were blinded to clinical information prior to results. Results: In 80/137 tumor pairs both copy number profiles met QC criteria and clonal relationship could be ascertained. In total 26/80 were considered related, 20/80 ambiguous and 34/40 non-related (Table 1). 16/26 ipsilateral subsequent cancers in IMPORT HIGH were clonally related to the primary tumor and could be considered true recurrences. In 5/26 it was impossible to accurately call clonality as pairs shared only common copy number changes such as 1q or 8q gain and 16q loss. 5/26 were considered new primaries. In the lower risk IMPORT LOW cohort, subsequent cancers appear to have similar chances of being related or independent. As expected, most contralateral tumors in IMPORT LOW showed no evidence of a clonal relationship to the index tumors. In both trials an ambiguous subgroup of pairs shared some common copy number changes suggesting similar phenotype.5/14 contralateral tumors in IMPORT HIGH, in which some women were also at high risk of systemic relapse, shared very similar copy number profiles to the index tumor and may be metastases rather than new primaries. Discussion: A considerable number of tumors classed as IBTR appear genomically unrelated to the index cancer particularly in low risk cancer; this biology is relevant to clinical management both initially and at ‘recurrence’. The finding that 5/14 contralateral cancers in the high risk group appear to be clonally related suggests that some may be metastases. Results are being confirmed by targeted sequencing and will be correlated with recorded spatial and clinicopathological data and patient outcome. Future work will analyse spatial relationships more precisely using deformable image registration. *From the 77 patients with baseline circulating tumor DNA samples, 2 patients were excluded because their samples failed during assay quality control. Table. PIK3CA and ESR1 alterations detected in circulating tumor DNA at baseline and post abemaciclib treatment Citation Format: Sara Lightowlers, Maria Roman-Escorza, Elena Provenzano, Judith Bliss, Jason Carroll, H Y Charlie Chan, Clare Griffin, Joanne Haviland, Monica Jefford, Anna Kirby, Navita Somaiah, Mark Sydenham, Jenny Titley, John Yarnold, Charlotte Coles, Elinor Sawyer. Genomic analysis of local recurrences following risk adapted breast radiotherapy in the IMPORT trials defines 'true recurrences' and 'new primaries' [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO5-22-04.

Abstract PO4-09-12: Academic-community partnership bridges disparities in African American patient representation in accelerated partial breast irradiation clinical trials

Abstract Purpose/Objectives: Clinical outcomes in African American (AA) patients diagnosed with breast cancer continue to lag behind other racial groups. Thus, AA women are 41% more likely to die from breast cancer than White women despite lower incidence of breast cancer in AA women. Some of these disparities are related to barriers in access to standard-of-care treatments such as radiation therapy (RT). The prolonged nature of radiation treatments confers disproportionate higher burden (due to lost wages, transportation costs etc.) on economically disadvantaged groups such as AA women. Accelerated partial breast irradiation (ABPI), which dramatically reduces treatment time in appropriately selected patients, has the potential to mitigate financial toxicity, and improve access and treatment compliance for AA. However, underrepresentation of AA patients in APBI trials may pose a barrier to wide adoption of APBI treatments in this patient population. At our institution, we have established a unique partnership between our University Hospital and a county hospital that serves as a safety-net hospital for many economically disadvantaged groups and treats a large proportion of AA patients. The goal of this study is to determine if our unique academic-community partnership improves disparities in representation of AA patients in APBI trials. Methods: We performed a PUBMED search to identify 197 clinical trials involving ABPI. After excluding international trials and multiple reports from the same trials, we identified 80 unique studies that were based in the United States. A total of 20 studies investigating APBI provided demographics data, comprising 1735 total patients. AA enrollment rate in these trials was compared to APBI trials completed at our institution in partnership with our county hospital partner. Results: Out of 1785 patients enrolled in APBI trials in the United States where demographic information was available, 1488 patients were White (85.7%), 124 were Black (7.1%), 67 were Hispanic (3.9%), and 46 were Asian (2.7%), and 10 patients were classified as multiple or unknown (0.6%). We compared these results to two APBI trials conducted at our institution investigating 5-fraction and single fraction APBI regimens. Out of a total of 104 patients treated, 17 patients (16.3%) were Black. This difference in proportion of AA patient enrollment between our institution (16.3%) versus those reported in APBI trials across the United States (7.1%) was statistically significant (p < 0.05). Conclusion: Reporting and representation of AA patients in APBI trials remains low, which may lead to lower adoption of APBI treatments in AA patients. This may lead to underutilization of APBI, a convenient treatment with lower financial toxicity, among AA patients. Our study shows that effective academic-community partnerships can bridge such disparities in AA patient representation in APBI trials. Expansion of such academic-community partnerships across the country may bridge systemic disparities in AA patient representation in oncology clinical trials. Future studies are needed to determine if improved access to novel and convenient treatments such APBI will bridge existing disparities in clinical outcomes in patients diagnosed with breast cancer. Citation Format: Ev Kakadiaris, Brian Lue, Young Suk Kwon, Prasanna Alluri, D Nathan Kim, Ann Sprangler, Mona Arbab, Robert Timmerman, Asal Rahimi. Academic-community partnership bridges disparities in African American patient representation in accelerated partial breast irradiation clinical trials [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO4-09-12.

Abstract PO1-03-06: Older patients with Early Stage Triple Negative Breast Cancer: The Memorial Sloan Kettering Cancer Center experience

Abstract INTRODUCTION Approximately 15% cases of TNBC are diagnosed in individuals over the age of 70. Older patients remain under-represented in clinical trials. We conducted a retrospective review of patients 70 years of age and older with stage I-III TNBC who were treated at Memorial Sloan Kettering Cancer Center (MSKCC), with the goal of describing the clinical practice patterns and outcomes. MATERIAL AND METHODS A retrospective record review of patients 70 years of age and older with a diagnosis of stage I-III TNBC between January 2015-December 2019 was performed. We report the data on the utilization of systemic chemotherapy and survival analyses. We compared patient characteristics by chemotherapy type using Wilcoxon rank sum test, Pearson’s Chi-squared test, and Fisher’s exact test. Overall Survival (OS), Breast Cancer Specific Survival (BCSS), and Recurrence Free BCSS (RF-BCSS) were examined using Cox proportional hazards models. All statistical analyses were conducted using R. RESULTS A total of 147 patients were included. The median age was 75 years (range 70-96). The number of patients with stage I, II, and III disease was 64 (44%), 66 (45%), 17 (12%), respectively. Twenty-five (18%) patients underwent comprehensive geriatric assessment. Out of total patients, 93 (63%) patients received systemic Chemotherapy (C) while 54 (37%) received no chemotherapy (NC). Patients receiving C were younger (median age 74 years with C vs. 78 years with NC, p< 0.001) and had a higher disease stage (Stage II-III: 66% (C) vs. 41% (NC), p=0.005). There were no significant differences in Activities of Daily Living (ADL) difficulty between both arms. Amongst, Instrumental ADL (IADL) assessment, patients in the NC group reported statistically significant greater difficulty with meal preparation (17% in NC and 4.3% in C, p=0.016). The most common reasons for not receiving chemotherapy were low-risk disease i.e. pT1aN0 or microinvasive (33%), patient preference (29%), and frailty per the treating oncologist (19%). Rate of mastectomy was higher in the NC group (35% in NC vs. 20% in C, p=0.029). Among the 32 patients who had radiation data, breast irradiation rates were higher in the C group (70% in C and 17% in NC, p=0.003). Thirty patients (20%) received neoadjuvant chemotherapy (NAC) and 65 (44%) received adjuvant chemotherapy. Anthracycline-based chemotherapy was the most common NAC (n=17, 57%). Patients who received Cyclophosphamide-Methotrexate-5-Fluorouracil (CMF) were older (age ≥75 years: 51% (CMF) vs. 17% (ACT),p=0.010), more likely treated in an adjuvant setting (87% CMF vs. 61% ACT, p=0.017), had earlier-stage disease (Stage 1: 54% (CMF) vs. 26% (ACT), p=0.028), and reported more ADL (31% in CMF vs. 0% in ACT, p=0.002) and IADL difficulties (31% CMF vs 4.3% in ACT, p=0.021). The use of Docetaxel/Cyclophosphamide (TC) and platinum-based regimens was low (8% and 5%, respectively). In the univariate analysis between the C and NC groups, there was no difference in OS (Hazard Ratio (HR) 0.78, 95% Confidence Interval (CI) 0.42-1.43; p=0.4), BCSS (HR 1.39, 95% CI 0.57-3.39; p=0.5), and RF-BCSS (HR 1.60, 95% CI 0.67-3.83; p=0.3). There was no difference in OS (HR 0.60, 95% CI 0.23-1.55; p=0.3), BCSS (HR 0.48, 95% CI 0.17-1.32; p=0.2), and RF-BCSS (HR 0.71, 95% CI 0.30-1.73; p=0.5) in patients receiving CMF vs. ACT. CONCLUSIONS In our single institutional experience, we observed that two-thirds of older patients with early-stage TNBC received systemic polychemotherapy. A third of patients with NC were very low risk (pT1a or microinvasive disease) which could explain lack of chemotherapy benefit in our study population. Use of CMF was more prevalent in patients aged ≥75, stage I disease, ADL/IADL difficulties, and in the adjuvant setting. We observed no difference in survival outcomes between the two chemotherapy regimens. CMF remains an efficacious option and a potentially viable alternative to ACT in TNBC, especially in the setting of early stage and advanced age. Citation Format: Jasmeet Singh, Diana Lake, West Dente-Ferguson, Yuan Chen, Fiona Erlich, Beatriz Korc-Grodzicki, Mark Robson, Larry Norton, W. Iris Zhi. Older patients with Early Stage Triple Negative Breast Cancer: The Memorial Sloan Kettering Cancer Center experience [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO1-03-06.

Abstract PS04-04: Adverse effects (AEs) reported via Patient Reported Outcome Measures (PROMs): A longitudinal analysis of the IMPORT HIGH breast radiotherapy trial (CRUK/06/003)

Abstract Background IMPORT HIGH is a multicentre phase III randomised controlled trial showing efficacy and safety of appropriately-dosed simultaneous integrated boost (SIB) in terms of local control, patient and clinician reported AEs among women with early breast cancer (BC)[1]. The PROMs sub-study collected baseline demographics and quality of life over 5 years. This exploratory analysis details the patient experience over time. Methods Women with higher-than-average risk of local relapse (≥18 years, breast conserving surgery, T1-3, pN0-pN3a, M0 invasive BC) were eligible. Randomisation (1:1:1) was between 40Gy whole breast and 16Gy sequential boost radiotherapy (control) and, 36Gy whole breast, 40Gy partial breast with either 48Gy SIB (test group 1), or 53Gy SIB (test group 2) radiotherapy. AEs from EORTC QLQ-BR23[2]; Body Image Scale (BIS)[3]; and protocol-specific (PS) items used in previous breast radiotherapy trials[4] were reported by patients at baseline (pre-randomisation), 6 months, and years 1, 3, 5. 24 AEs[4] were included in the analysis, dichotomised as none/mild versus moderate/marked. Anxiety and depression were measured over 5 years using Hospital Anxiety and Depression Scale. Surgical deficit was scored from baseline photographs. Multivariable generalized estimating equation models were fitted for each AE. Potential baseline predictors included those used previously[4] plus ethnicity, smoking, deprivation, employment, cardiovascular disease history, post-operative infection, haematoma, post-surgery complication. Backwards selection and Quasi-likelihood criterion were used for model selection. Results Between 2009-2013, 1338 patients were offered the PROMs sub-study and 1078 (81%) participated. Median age was 48.8 years (IQR 44.0-54.9). 17% reported ‘Borderline’ or 14% ‘Case’ anxiety at baseline. 11% reported ‘Borderline’ or 7% ‘Case’ depression at baseline. 747/1015 (74%), 686/986 (70%), 604/916 (66%), 532/845 (63%), 461/709 (65%) of participants reported at least 1 moderate/marked AE at baseline, 6 months, 1, 3 and 5 years. Number of moderate/marked AEs reported per person reduced over time after year 1 (p < 0.005). BIS reported moderate/marked AEs (except dissatisfaction with scar) decreased, whereas individual items from BR23 and PS items showed mixed patterns of reporting (increased, decreased, stayed the same) over time (Table 1). From multivariable analysis, ‘Borderline’ or ‘Case’ depression or anxiety (time-varying) was associated with increased reports for almost all AEs. Chemotherapy and younger age were associated with increased reports of moderate/marked AEs for items in BIS, and large surgical deficit predicted more breast symptoms. Conclusion Change of overall breast appearance was the most reported moderate/marked AE that persisted over time.Although patients reported fewer moderate/marked AEs over time, trends in individual moderate/marked AEs showed mixed patterns. This study identified factors associated with increased risks of patient-reported moderate/marked AEs. Early identification of patients more likely to report AEs could facilitate implementation of targeted support.

Abstract PO1-03-05: Tolerance of adjuvant radiotherapy combined with pembrolizumab for triple negative breast cancer

Abstract BACKGROUND AND PURPOSE: The current standard-of-care management of locally advanced triple negative breast cancer (TNBC) is based on neoadjuvant chemo-immunotherapy with pembrolizumab, surgery, radiotherapy and adjuvant pembrolizumab. However, the safety of combining pembrolizumab with adjuvant breast radiotherapy has never been evaluated. This study evaluated the tolerance profile of concurrent pembrolizumab (P) with adjuvant radiotherapy (RT) in locally advanced TNBC patients. METHODS: This bicentric ambispective study included the first prospectively registered patients with non-metastatic TNBC treated with the KEYNOTE-522 regimen in our institution. They received P in combination with carboplatin and paclitaxel chemotherapy and a second chemotherapy with doxorubicin and cyclophosphamide, followed by surgery and locoregional RT with or without P as adjuvant treatment. RT was normo- or hypofractionated, for the breast or chest wall, with or without lymph node irradiation according to institutional guidelines. Adjuvant P was administered at a total dose of 1800 mg at 200 mg once every 3 weeks or 400 mg once every 6 weeks. The safety profile was evaluated during and after the end of RT (until the last contact) with CTCAE V.5 scale. RESULTS: A total of 55 patients (pts) were prospectively included between July 2021 and March 2023. The median age was 49 years (29-69). The median follow-up was 12 months ( range, 10-26). Of them, 27 (49%) did not receive P concomitantly with RT (RT-only group) because of neo-adjuvant treatment related toxicities, and 28 (51%) received P concomitantly with RT (P-RT group). There was no statistical difference in population and toxicity between the RT-only group and the P-RT group. Nine patients were diagnosed with cardiac toxicities before the beginning of the RT and did not receive P during the RT. No RT-induced grade ≥4 toxicities were observed. Early toxicities were mainly grade 1-2. Two grade 3 toxicities occurred (1 case of axillary pain in the P-RT group and 1 radiodermatitis in the RT-only group). No cardiac or pulmonary toxicities ≥grade 2 were observed with adjuvant therapy. The toxicity profile is given in table 1. DISCUSSION: In these series, the main cause of discontinuation of pembrolizumab was related to suspicion of cardiac adverse events occurring during the neoadjuvant treatment and related to the injection of pembrolizumab or of the chemotherapy. All myocarditis happened before radiotherapy and did not affect the administration of radiotherapy. In this context, the optimal radiotherapy technique and cardiac dose constraints after ICI-induced myocarditis is unknown and late cardiotoxicity studies will be needed to precise these points. Cardiac sparing techniques, such as deep-inspiration breath hold, proton therapy, or alternative positioning (such as isocentric lateral decubitus) could be considered. CONCLUSION: Adjuvant radiotherapy can be combined with pembrolizumab for TNBC patients without increasing the risk of radiation-induced adverse events, allowing maintaining a systemic treatment in these high-risk patients. Longer follow-up and prospective studies are needed to validate these results. Adjuvant treatment-related adverse events Citation Format: Youlia Kirova, Thaïs Tison, Pierre Loap, Emilie ARNAUD, Kim Cao, Solène Bringer, Manon Kissel, Safia Maaradji, Juliette Mainguene, Jean-Yves Pierga, Florence Lerebours, Anne Salomon, Mariana Mirabelle, Delphine Loirat, Francois-Clement Bidard. Tolerance of adjuvant radiotherapy combined with pembrolizumab for triple negative breast cancer [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO1-03-05.

Abstract PO1-22-02: Optimal intra-fraction PTV margins for patients receiving stereotactic partial breast radiation (SPBI) using cone beam adaptive radiation therapy

Abstract Objectives To quantify the intra-fraction tumor bed motion using image guidance and fiducial markers to determine optimal PTV margins in early-stage breast cancer patients receiving adaptive radiation therapy SPBI after partial mastectomy. Methods A retrospective cohort of five patients with pT1a-pT2N0, grade 1-2, ER+/PR+ early-stage invasive ductal carcinoma of either the right breast or left breast underwent partial mastectomy and adjuvant five-fraction SPBI using cone beam based online adaptation. A total of 62 CBCTs and 22 total fractions were analyzed after post-processing with an average time span of 39.1±8.9 minutes. Two methods were utilized to determine optimal CTV to PTV margins: one contouring-based and another fiducial-based. Our contouring-based method involved independently contouring on each fraction’s CBCTs including pre-treatment CBCT, intra-treatment CBCT, and post-treatment CBCT. After image registration with the original simulation CT image, these contours were propagated to and combined to create a new union CTV. Using the original CTV on the simulation CT, optimal PTV margin was determined to achieve 95% overlap of the union CTV created from fractionated CBCTs. In addition to the contouring-based method, our fiducial-based method utilized an in-house script to calculate the centroid of all fiducials per CBCT. The average and maximum anterior-posterior, medial-lateral, superior-inferior shifts of fiducials between intra-fraction CBCTs were recorded. Results Using our contouring-based method, we calculated and determined that a uniform 3.5 mm expansion around the original CT simulation CTV is needed to achieve 95% PTV overlap encompassing the pre-treatment, intra-treatment, and post-treatment union CTV. Furthermore, with our fiducial-based method, we calculated average centroid anterior-posterior, medial-lateral and superior-inferior shifts to be the following: 1.51±0.79mm, 1.04±0.55 mm, 1.78±0.94 mm respectively. Average maximum shifts were determined to be 2.13±1.18mm anterior-posterior, 1.45±0.76mm medial-lateral and 2.47±1.40mm superior-inferior shifts. Conclusion With our contouring-based analysis, this preliminarily study suggests CTV to PTV margin of 3.5mm is adequate. On the other hand, our fiducial-based method suggests decreased movement and smaller asymmetric margin. Further CBCT adaptation images will be analyzed. In conjunction with these two methods, we currently recommend utilizing a 3.5mm uniform margin for intrafraction motion and to assess adequate coverage with image guidance during daily adaptation for patients with early-stage breast cancer receiving SPBI. Citation Format: Meng-Lun Hsieh, Justin Visak, Sean Domal, Gabrielle Gard, Steven Montalvo, Liyuan Chen, Xinran Zhong, Zohaib Iqbal, Tingliang Zhuang, Bin Cai, Heejung Kim, Mona Arbab, Prasanna Alluri, Nathan Kim, Mu-Han Lin, David Parsons, Asal Rahimi. Optimal intra-fraction PTV margins for patients receiving stereotactic partial breast radiation (SPBI) using cone beam adaptive radiation therapy [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO1-22-02.

Surgical Treatment of Breast Lymphedema: A Distinct Pathology With Unique Challenges.

Supermicrosurgical advances such as lymphovenous bypass (LVB) have enabled effective physiologic treatment of lymphedema affecting the extremities. Reports of surgical treatment for breast lymphedema (BL) are sparse, consisting of case reports and almost exclusively LVB. We report our experience with BL, including a case of mastectomy and breast reconstruction with abdominal free flap and inguinal vascularized lymph node transfer (VLNT) for BL. We compare our series with the surgical literature to discern unique characteristics and treatment limitations inherent to this disease. A database was prospectively maintained from September 2020 to May 2023 including all patients diagnosed with BL who were referred to our institution. Breast lymphedema was diagnosed using clinical criteria, and relevant patient data were recorded. Patients interested in surgical management underwent indocyanine green lymphography to determine candidacy for LVB or other interventions. All patients, including those surgically managed, were treated with complex decongestive therapy. Nine patients with BL were included. Eight had undergone breast-conserving therapy for breast cancer with whole breast irradiation. One patient was treated for Hodgkin lymphoma with axillary lymphadenectomy and axillary radiation. Indocyanine green lymphography was performed in 6 patients, of which 4 patients had diffuse dermal backflow. Two patients had lymphatic targets suitable for LVB, including the patient without breast irradiation. Three patients were managed surgically. One patient without bypass targets underwent breast reduction with partial symptomatic relief, later followed by a mastectomy with abdominal free flap reconstruction and VLNT. Two patients with suitable bypass targets underwent LVB, with resolution of breast swelling and subjective symptoms. The diffuse lymphatic obliteration due to radiation field effect in BL results in a distinct pathophysiology compared with extremity lymphedema. Although published reports of surgical BL treatment almost exclusively describe LVB, other surgical options may be more frequently required. Ablative strategies such as mastectomy and regenerative techniques such as VLNT should be considered potential first-line treatment options for these patients.

1568: Toward multi-institutional Knowledge-Based benchmark for right and left whole breast irradiation

1568: Toward multi-institutional Knowledge-Based benchmark for right and left whole breast irradiation

2516: NTCP model of acute toxicity after whole breast irradiation: training and extended validation

2516: NTCP model of acute toxicity after whole breast irradiation: training and extended validation

Effectiveness of multi-criteria optimization in combination with knowledge-based modeling in radiotherapy of left-sided breast including regional nodes

Multi-criteria optimization (MCO) is a method that was added to treatment planning to create high-quality treatment plans. This study aimed to investigate the effectiveness of MCO in combination with knowledge-based planning (KBP) in radiotherapy for left-sided breasts, including regional nodes. Dose/volume parameters were evaluated for manual plans (MP), KBP, and KBP + MCO. Planning target volume doses of MP had better coverage while KBP + MCO plans demonstrated the lowest organ at risk doses. KBP and KBP + MCO plans had increasing complexity as expressed in the number of monitor units.

Development of an ai prediction model for arm lymphoedema following breast cancer surgery and radiotherapy

Development of an ai prediction model for arm lymphoedema following breast cancer surgery and radiotherapy

A Radiation Therapy Contouring Atlas for Delineation of the Level I and II Axillae in the Prone Position: A Single-Institution Experience

With transition from supine to prone position, tenting of the pectoralis major occurs, displacing the muscle from the chest wall and shifting the level I and II axillary spaces. For patients for whom we aim to treat the level I and II axillae using the prone technique, accurate delineation of these nodal regions is necessary. Although different consensus guidelines exist for delineation of nodal anatomy in supine position, to our knowledge, there are no contouring guidelines in the prone position that account for this change in nodal anatomy. The level I and II nodal contours from the Radiation Therapy Oncology Group (RTOG) breast cancer supine atlas were adapted for prone position by 2 radiation oncologists and a breast radiologist based on anatomic changes observed from supine to prone positioning on preoperative diagnostic imaging. Forty-three patients from a single institution treated with prone high tangents from 2012 to 2018 were identified as representative cases to delineate the revised level I and II axillae on noncontrast computed tomography (CT) scans obtained during radiation simulation. The revised nodal contours were reviewed by an expanded expert multidisciplinary panel including breast radiologists, radiation oncologists, and surgical oncologists for consistency and reproducibility. Consensus was achieved among the panel in order to create modifications from the RTOG breast atlas for CT-based contouring of the level I and II axillae in prone position using bone, muscle, and skin as landmarks. This atlas provides representative examples and accompanying descriptions for the changes described to the caudal and anterior borders of level II and the anterior, posterior, medial, and lateral borders of level I. A step-by-step guide is provided for properly identifying the revised anterior border of the level I axilla. The adaptations to the RTOG breast cancer atlas for prone positioning will enable radiation oncologists to more accurately target the level I and II axillae when the axillae are targets in addition to the breast.

2855: Link between extent of acute breast skin dermatitis and radiation dose following proton therapy.

2855: Link between extent of acute breast skin dermatitis and radiation dose following proton therapy.

1014: Dosimetric evaluation of accelerated partial breast irradiation using VMAT technique

1014: Dosimetric evaluation of accelerated partial breast irradiation using VMAT technique

727: Stereotactic Partial Breast Irradiation: 4-year Clinical Results and Cosmetic Outcomes

727: Stereotactic Partial Breast Irradiation: 4-year Clinical Results and Cosmetic Outcomes

1095: Whole Breast versus Partial Breast Irradiation for early-stage breast cancer: the HYPAB trial

1095: Whole Breast versus Partial Breast Irradiation for early-stage breast cancer: the HYPAB trial

2246: Five-year results of Very Accelerated Partial Breast Irradiation VAPBI phase I-II GEC-ESTRO trial

2246: Five-year results of Very Accelerated Partial Breast Irradiation VAPBI phase I-II GEC-ESTRO trial

3200: Ultra versus moderate-hypofractionation in Partial Breast Irradiation.

3200: Ultra versus moderate-hypofractionation in Partial Breast Irradiation.

2997: Comprehensive cosmesis evaluation of ultrahypofractionated adjuvant breast radiotherapy with SIB

2997: Comprehensive cosmesis evaluation of ultrahypofractionated adjuvant breast radiotherapy with SIB