Postmastectomy Radiation Research Articles

Patient-Reported Outcomes Improve Following Mastectomy for Early-Stage Breast Cancer in Nigeria: Pilot Experience Using a Translated and Validated BREAST-Q

PURPOSE Mastectomy without reconstruction is recommended for most Nigerian women with non-metastatic breast cancer (BC), but only 43% receive surgery, partly due to psychosocial factors. Patient-reported outcome measures (PROMs) are valuable tools for improving patient-centered care. BREAST-Q is a validated PROM for evaluating satisfaction and health-related quality of life after BC surgery. This research aimed to measure the effect of mastectomy on PROMs across BC stages in Nigeria, using BREAST-Q for the first time in this setting. METHODS A psychometrically validated, Yoruba version of the BREAST-Q mastectomy module was administered pre-operatively and at multiple time-points post-operatively to Nigerian women with non-metastatic BC undergoing mastectomy at three academic institutions. Domains: psychosocial well-being, physical well-being chest, sexual well-being and satisfaction with breasts, had both pre-and post-operative applicability. BREAST-Q scores were transformed into RASCH equivalents (0=worst, 100=best). Differences between scores pre-operatively and at 6-months post-operatively were compared using a paired t-test within early-stage (I/II) and late-stage (III) cohorts. RESULTS 108 patients had a median age of 50 (IQR 43, 59). 102 had documented stage: I–5 (5%), II–42 (41%), and III–55 (54%). 90 (83%) received neoadjuvant chemotherapy. 12 (11%) received post-mastectomy radiation. Mean pre-operative BREAST-Q scores across all domains were lower for early- vs. late-stage disease. Patients with early-stage BC had significantly higher mean BREAST-Q scores at 6-months post-operatively than pre-operatively in three of four domains: psychosocial well-being (pre-op: 60/post-op: 67, p-value=0.024), physical well-being chest (pre-op: 13/post-op: 27, p-value<0.001), and satisfaction with breasts (pre-op: 55/post-op: 65, p-value=0.031). Sexual well-being was not significantly different between time-points (pre-op: 29/post-op: 24, p-value=0.3). In patients with late-stage BC, psychosocial well-being (pre-op: 66/post-op: 67, p-value=0.6), physical well-being chest (pre-op: 22/post-op: 20, p-value=0.5), and satisfaction with breasts (pre-op: 58/post-op: 52, p-value=0.13) scores were similar pre- and 6-months post-operatively. Sexual well-being decreased significantly at 6-months (pre-op: 42/post-op: 25, p-value<0.001). CONCLUSION We report the first-ever use of the BREAST-Q in Nigeria. PROMs following mastectomy were unchanged or better in most domains. Significant improvement was seen in patients with early-stage disease. These results can inform pre-operative patient counseling to guide expectations and reduce fear. Interventions to improve sexual well-being are needed for patients with late-stage disease.

Hypofractionated versus Conventional Postmastectomy Irradiation for Breast Cancer: Comparison of Acute Skin Toxicity.

Breast cancer is the leading cause of cancer mortality among women. Radiotherapy can reduce recurrence and prolong survival of patients accepting breast-conserving surgery (BCS). This study aims to compare acute skin reactions in patients receiving hypofractionated versus conventional radiotherapy at a single institution and to summarize the relevant influencing factors. This study analyzed 152 patients who underwent either hypofractionated or conventional whole-breast irradiation (WBI) after BCS. Acute skin toxicity was assessed according to the Radiation Therapy Oncology Group (RTOG) criteria. Predictive factors for acute skin toxicity were identified using multivariate analysis and visualized using a forest spot. Grade 0 reactions occurred in 75.34% vs 70.89%, grade 1 in 16.44% vs 15.19%, grade 2 in 8.22% vs 12.66%, and grade 3 in 0% vs 1.27% of patients receiving hypofractionated and conventional WBI, respectively. There was no statistically significant difference in acute skin reaction in patients treated with hypofractionated radiation compared with conventional radiation (P = 0.62). Multivariate analysis revealed that metastatic lymph nodes (P = 0.021), whole-breast planning target volume (PTV-WB) (P < 0.001), and tumor bed planning target volume (PTV-TB) (P = 0.002) were significantly correlated with higher rates of acute skin toxicity. Hypofractionated WBI demonstrated similar acute skin adverse reactions compared to conventional WBI. These findings indicate that hypofractionated radiotherapy offers comparable tolerance, equivalent curative effect, convenience, andeconomic benefits, supporting its clinicalpromotion.

Arm morbidity and financial difficulty in breast cancer survivors.

Long-term upper extremity symptoms after breast cancer treatment may impact patient-reported financial difficulty. In this cross-sectional investigation, we hypothesized that severity of arm symptoms would be associated with greater financial difficulty. Stage 0-III breast cancer patients treated at our institution from 2002 to 2012 were recruited for a 2018 survey study appraising disease-specific patient-centered outcomes using EORTC-QLQ-BR23 and EORTC-QLQ-C30 questionnaires. The association between Arm Symptom (AS) score and Financial Impact (FI) score was assessed, adjusting for clinically relevant variables. Of 1126 interested participants, 882 (78%) responded to surveys. Three hundred fourteen (36%) with incomplete responses were excluded. Median time from surgery was 9years; 181 (32%) and 117 (21%) had mastectomy with or without reconstruction, 126 (22%) received postmastectomy radiation (PMRT), and 221 (39%) underwent axillary lymph node dissection. 76 (13%) reported some degree of financial difficulty; 10 (2%) the highest degree of difficulty. Of 217 (38%) patients experiencing arm symptoms, 60 (28%) had severe symptoms. Seven (70%) of those with highest degree of financial difficulty had severe arm symptoms. Younger age at surgery (p = .029), mastectomy with reconstruction (p = 0.003), Hispanic ethnicity (p < 0.001), PMRT (p = 0.027), recurrence (p < 0.001), and higher AS score (p < 0.001) were associated with greater financial difficulty. On multivariable analysis, AS score, younger age, Hispanic ethnicity, and recurrence remained associated with financial difficulty. In this study, younger age, Hispanic ethnicity, and arm morbidity were associated with increased risk for financial difficulty. Clarifying how treatment-related adverse events such as arm morbidity increase financial hardship may guide interventions to mitigate this burden.

Prognosis of isolated locoregional recurrence after early breast cancer with immediate breast reconstruction surgery: a retrospective multi‑institutional study.

The prognosis in patients with breast cancer with isolated locoregional recurrence (ILRR) without simultaneous distant metastases after immediate breast reconstruction (IBR) remains unknown. We aimed to investigate the prognosis in this patient population. This multi-institutional retrospective observational study evaluated 3295 patients with primary breast cancer who underwent IBR at 12 Japanese medical facilities between January 1, 2008 and December 31, 2016. The outcome measures were the prognostic factors for ILRR after IBR, 5-year distant metastasis-free interval (DMFI), and 5-year overall survival (OS). Mastectomy or skin-sparing mastectomy was performed in 3295 patients. ILRR occurred in 70 patients, and the median observation period from ILRR diagnosis was 39.3months. Of the 70 patients, 9 (12.9%) had axillary lymph node recurrence (ALNR) at the time of ILRR diagnosis. The 5-year DMFI and OS rates after ILRR were 92.4% and 91.2%, respectively. Pathological lymph node metastasis at primary surgery (P = 0.041) and ALNR (P = 0.022) at ILRR were significantly associated with DMFI in the univariate analysis. ALNR was the only independent prognostic factor in the multivariate analysis (P = 0.041). Post-mastectomy radiation therapy (PMRT; P = 0.022) and ALNR (P = 0.043) were significantly associated with OS in the univariate analysis, and both PMRT (P = 0.010) and ALNR (P = 0.028) were independent prognostic factors in the multivariate analysis for OS. Although patients with breast cancer who had ILRR after IBR have favorable prognosis, ALNR may lead to poor prognosis. To the best of our knowledge, this study is the first to report the prognosis of these patients.

Impact of Implant Exchange Timing after Post-Mastectomy Radiation in Immediate Tissue Expander Breast Reconstruction: A Systematic Review.

The use of post-mastectomy radiation therapy (PMRT) in the setting of immediate two-stage breast reconstruction is becoming increasingly widespread. However, the timeframe of tissue expander exchange for permanent implant placement following PMRT is not well-defined, and it remains unclear what time interval optimizes surgical outcomes and patient satisfaction. A systematic review conducted in accordance with PRISMA 2020 was completed. PubMed, Embase, Scopus, and Cochrane databases were searched under keywords pertaining to concepts of tissue expander breast reconstruction and PMRT. Inclusion criteria encompassed primary articles on tissue expander breast reconstruction with adjuvant radiation therapy reporting timing of exchange to permanent implant following radiation and surgical outcomes. Of the initial 1,259 publications, 15 studies met our inclusion criteria, and 11 studies had granular enough data to use for pooled analysis. Implant exchange less than 6 months after PMRT was found to be associated with increased incidence of wound dehiscence (17.12% vs 3.64%, p<0.001) and hematoma (25% vs 2.59%, p<0.001) compared to exchange after 6 months. There was no significant difference in incidence of SSI, seroma, capsular contracture, and reconstructive failure. Expander to implant exchange at less than 6 months is associated with a higher incidence of wound dehiscence and hematoma formation but does not increase the risk of reconstruction failure. The limited research on ideal timing prompts further investigation to optimize surgical outcomes for the increasing patient population undergoing PMRT and immediate two-staged breast reconstruction.

Assessment of 3D-Printed Bolus for Post-Mastectomy Breast Cancer Radiation Therapy

Assessment of 3D-Printed Bolus for Post-Mastectomy Breast Cancer Radiation Therapy

A nationwide study of breast reconstruction after mastectomy in patients with breast cancer receiving postmastectomy radiotherapy: comparison of complications according to radiotherapy fractionation and reconstruction procedures

BackgroundWe examined the patterns of breast reconstruction postmastectomy in breast cancer patients undergoing postmastectomy radiotherapy (PMRT) and compared complications based on radiotherapy fractionation and reconstruction procedures.MethodsUsing National Health Insurance Service (NHIS) data (2015–2020), we analysed 4669 breast cancer patients with PMRT and reconstruction. Using propensity matching, cohorts for hypofractionated fractionation (HF) and conventional fractionation (CF) were created, adjusting for relevant factors and identifying grade ≥3 complications.ResultOf 4,669 patients, 30.6% underwent HF and 69.4% CF. The use of HF has increased from 19.4% in 2015 to 41.0% in 2020. Immediate autologous (32.9%) and delayed two-stage implant reconstruction (33.9%) were common. Complication rates for immediate (N = 1286) and delayed two-stage (N = 784) reconstruction were similar between HF and CF groups (5.1% vs. 5.4%, P = 0.803, and 10.5% vs. 10.7%, P = 0.856, respectively) with median follow-ups of 2.5 and 2.6 years. HF showed no increased risk of complications across reconstruction methods.ConclusionA nationwide cohort study revealed no significant difference in complication rates between the HF and CF groups, indicating HF for reconstructed breasts is comparable to CF. However, consultation regarding the fractionation for reconstructed breast cancer patients may still be necessary.

Ipsilateral recurrence and breast cancer outcomes in carriers of BRCA1/2 pathogenic variants according to locoregional treatments.

e12584 Background: Our previous study of 255 breast cancer (BC) patients, carriers of BRCA1/2 pathogenic variants (PV), showed that patients who underwent mastectomy without post-mastectomy radiotherapy (PMRT) had higher rates of local recurrence (LR) than those who underwent PMRT or breast-conserving therapy (BCT). Our aim was to verify our previous findings in a larger cohort. Methods: Clinical data was extracted from the medical records of BRCA1/2 mutation carriers with BC, treated at a single institution between 1/2006-12/2022. Data extracted included demographics, tumor characteristics, disease stage, surgical and oncological treatment, use of RT and disease outcomes. Results: Overall, 481 BC patients with BRCA1/2 germline mutations were identified, 20 of them presented with synchronous bilateral disease. Median follow-up time was 75.3 months (range 12.5-211). After excluding 16 patients with metastatic de novo disease and 1 patient not operated for medical reasons, 464 patients with 484 primary tumors were analyzed. Of these, 234 (48.3%) mastectomies (84% were skin- or nipple-sparing, SSM/NSM, 16% total mastectomy) and 250 (51.7%) BCT were performed. In the non-PMRT group (n=153) there was earlier disease stage at diagnosis (77.6% of tumors were Tis and T1N0) compared to the PMRT group (n=81) and BCT group (4.9% and 45%, respectively, p&lt;0.001). All had free surgical margins. LR rate in the study cohorts was 20/153 breasts (13.1%) in the non-PMRT group compared with 1/81 breasts (1.2%) in the PMRT group (p=0.003), and 16/250 (6.4%) in the BCS group (p=0.024). All but one recurrence were invasive. Cumulative incidence of LR at 5 and 10 years was 14.1% and 15.9% in the non-PMRT, compared to 4.4% and 9.4% in BCT group, respectively (p=0.034). No significant difference in overall survival was observed (p=0.39). Conclusions: BRCA1/2 PV carriers treated with mastectomy without PMRT had higher rates of LR than those who underwent mastectomy and PMRT or BCT, despite earlier stage disease. Further studies are needed to compare these outcomes to non- BRCA1/2 carriers and find means to improve local control in these patients.

Predicting locoregional recurrence in triple-negative breast cancer using novel molecular subtyping.

e12549 Background: Triple-negative breast cancer (TNBC) presents a poorer prognosis compared to other breast cancer subtypes, characterized by a higher likelihood of early recurrence and increased incidence of visceral metastases. Evidence from numerous randomized clinical trials indicates that postmastectomy radiotherapy (PMRT) reduces locoregional recurrence (LRR) and improves breast cancer survival in TNBC. Previous reports creatively divided TNBC into four molecular subtypes for personalized treatment. The present study aims to elucidate patterns of LRR in different subtypes of TNBC after PMRT. Methods: From 2019 to 2022, data from 349 AJCC 7th edition stage II-III breast cancer patients treated with mastectomy and PMRT were retrospectively analyzed. These patients were classified into the basal-like immune-suppressed (BLIS) and non-BLIS groups based on the immunohistochemistry biomarkers. The cumulative incidence function was applied to estimated LRR rates, with death as a competing risk, using Gray's test for comparisons. Results: According to the IHC results, a total of 255 patients belonged to the non-BLIS group and 94 to the BLIS group. The 3-year LRR for the entire cohort was 5.16%. There were 9 cases each in the non-BLIS subtype (3.5%) and BLIS subtype (9.6%). The cumulative incidence of LRR between the two groups was significantly different, with a rate of 4.0% in the non-BLIS group and 9.0% in the BLIS group ( P = 0.02). Among the 18 patients with LRR in the whole population, 11 had isolated LRR and 7 were diagnosed with LRR with concurrent distant metastases. The most common area of recurrence in both subtypes was the supraclavicular region. The majority of recurrences occurred within the RT field (in-field), and no isolated out-of-field relapse was observed. In multivariate analysis, independent factors predicting higher LRR were the BLIS subtype (HR = 3.06, P = 0.02). Conclusions: Study results suggest that TNBC of the BLIS subtype is at higher risk for LRR. Immunohistochemistry-based molecular typing may serve as a prognostic biomarker to guide postmastectomy radiotherapy in patients with TNBC. New strategies are needed to improve local control rates in patients with BLIS subtype.

Prognosis of locoregional recurrence after early breast cancer with immediate breast reconstruction.

e12595 Background: Several studies have shown no difference in the prognosis of breast cancer patients who underwent total mastectomy (MT) with or without immediate breast reconstruction (IBR), which is now a standard surgical technique in the treatment of breast cancer. While some studies have reported a poor prognosis for locoregional recurrence (LRR) following breast cancer surgery, the prognosis of LRR without simultaneous distant metastasis after IBR is not known. We conducted a multi-facility retrospective observational study to investigate the prognosis of breast cancer patients with LRR after IBR. Methods: Of the 4,726 primary breast cancer patients for whom IBR was performed at 12 Japanese medical facilities between January 1, 2008, and December 31, 2016, MT or skin-sparing mastectomy (SSM) was performed in 3,295 patients. LRR was observed in 87 of these patients, 17 of whom had distant metastasis (n=13) or metastasis to the supraclavicular or internal mammary lymph nodes (n=4) before LRR was excluded. The measured outcomes were IBR-LRR-related prognostic factors, five-year distant metastasis-free survival (DMFS), and five-year overall survival (OS). The statistical analyses employed Kaplan–Meier curves and a Cox proportional hazards model. Results: The median observation period was 39.3 months and the median age at which IBR was performed was 44 years. There were 61 cases (87.1%) of invasive cancer. Sixty-one cases (87.1%) were ER-positive, 54 (77.1%) were PR-positive, and 13 (19.7%) were HER2-positive. Fifteen cases (21.4%) had pathological lymph node metastasis (pN), 60 cases (85.7%) underwent implant reconstruction, 33 cases (47.1%) had a disease-free interval ≤ 36 months, 9 cases (12.9%) had regional lymph node recurrence (RR), and 65 cases (92.9%) underwent surgical resection to treat LRR. The five-year DMFS after LRR was 92.4%, and the five-year OS was 91.2%. The relationship between DMFS and clinical pathology factors was analyzed using a Cox proportional hazards model. Univariate analysis revealed significant differences for pN (HR 10.634, 95% CI 1.102–102.616, P=0.041) and RR (HR 9.960, 95% CI 1.400–70.862, P=0.022), and multivariate analysis indicated that RR was the only independent prognostic factor for DMFS (HR 7.834, 95% CI 1.085–56.587, P=0.041) (Table 1). Univariate analysis revealed significant differences for post-mastectomy radiation therapy (PMRT) (HR 130.676, 95% CI 1.552–412.278, P=0.023) and RR (HR 8.181, 95% CI 1.106–60.503, P=0.043), and multivariate analysis indicated that both PMRT (HR 61.281, 95% CI 2.540–1478.426, P=0.010) and RR (HR 15.687, 95% CI 1.354–181.772, P=0.028) were independent prognostic factors for OS. Conclusions: This is the first study to report the prognosis of breast cancer patients with LRR after IBR. Although these patients have a favorable prognosis overall, our results indicate that RR may be a significant factor for poor prognosis.

Reconstructive plastic surgery in combined treatment of breast cancer: Predictive risk factors of complications and reconstruction failure.

e12594 Background: Breast reconstruction after mastectomy must consider potential complications from surgical techniques as well as additional complications of oncologic treatment such as radiation or systemic therapy. But the consensus is lacking regarding the optimal reconstruction plan for patients requiring adjuvant radiation therapy. Objective: To determine the impact of risk factors on the development complications of breast reconstruction for postmastectomy radiotherapy. Methods: This study included patients diagnosed with breast cancer who received combination treatment from 2016 to 2021 at the FSBI “N.N. Petrov National Medical Research Center of Oncology” of the Russian Ministry of Health. The patients were divided into 3 groups: immediate reconstruction (158 people), immediate-delayed (210 people) and delayed (98 people). Results: Every fourth patient (24.0%, 112/466) may encounter a complication after mastectomy with reconstruction and adjuvant radiation therapy. According to the analyzed data, there was no correlation between potential risk factors depending on the general status of patients (age, obesity, diabetes mellitus, hypertension, history of smoking) and the occurrence of complications after combination treatment. Conclusions: The analysis of complications and reconstructive failures showed that immediate breast reconstruction at the FSBI "N.N. Petrov National Medical Research Center of Oncology" of the Ministry of Health of Russia is the safest method of reconstruction in the combined treatment of breast cancer with the lowest incidence of severe complications (9.5%, 15/158, z&gt;1.96), which plays a key role in the development of reconstructive failures (Pearson Correlation=0.861, p&lt;0.001). However, these surgeries are associated with a significant number of capsular contractures (15.2%, 24/158, z&gt;1.96, Pearson Correlation=0.230, p&lt;0.001), which requires finding ways to minimize these risks to optimize treatment in each individual case in short and long term results.

The impact of the new ESTRO-ACROP target volume delineation guidelines for postmastectomy radiotherapy after implant-based breast reconstruction on breast complications

The European Society for Radiotherapy and Oncology–Advisory Committee in Radiation Oncology Practice (ESTRO-ACROP) updated a new target volume delineation guideline for postmastectomy radiotherapy (PMRT) after implant-based reconstruction. This study aimed to evaluate the impact on breast complications with the new guideline compared to the conventional guidelines. In total, 308 patients who underwent PMRT after tissue expander or permanent implant insertion from 2016 to 2021 were included; 184 received PMRT by the new ESTRO-ACROP target delineation (ESTRO-T), and 124 by conventional target delineation (CONV-T). The endpoints were major breast complications (infection, necrosis, dehiscence, capsular contracture, animation deformity, and rupture) requiring re-operation or re-hospitalization and any grade ≥2 breast complications. With a median follow-up of 36.4 months, the cumulative incidence rates of major breast complications at 1, 2, and 3 years were 6.6%, 10.3%, and 12.6% in the ESTRO-T group, and 9.7%, 15.4%, and 16.3% in the CONV-T group; it did not show a significant difference between the groups (p = 0.56). In multivariable analyses, target delineation is not associated with the major complications (sHR = 0.87; p = 0.77). There was no significant difference in any breast complications (3-year incidence, 18.9% vs. 23.3%, respectively; p = 0.56). Symptomatic RT-induced pneumonitis was developed in six (3.2%) and three (2.4%) patients, respectively. One local recurrence occurred in the ESTRO-T group, which was within the ESTRO-target volume. The new ESTRO-ACROP target volume guideline did not demonstrate significant differences in major or any breast complications, although it showed a tendency of reduced complication risks. As the dosimetric benefits of normal organs and comparable oncologic outcomes have been reported, further analyses with long-term follow-up are necessary to evaluate whether it could be connected to better clinical outcomes.

Feasibility and Toxicity of Hypofractionated Radiation Therapy in Patients Undergoing Post Mastectomy Radiation Therapy

Introduction: Post mastectomy radiation (PMRT) plays major role in breast cancer treatment. Hypofractionated radiation is a relatively newer modality. Hypofractionation is more commonly used after breast conservation surgery. Landmark trials that studied hypofractionation had fewer PMRT subjects. Here we report our study on feasibility and toxicity profile of hypofractionated PMRT. Aim: To describe the clinical and toxicity profile of patients undergoing hypofractionated 3D conformal radiation therapy in breast cancer patients. Materials &amp; Methods: This study included patients who are eligible for post mastectomy radiation therapy above 18 years planned for adjuvant PMRT (40.05Gy in 15 fractions delivered over 3 weeks in 3D conformal radiation) to the chest wall and supraclavicular nodes between April 2021 to October 2022., active lung infection, patient preference for conventional fractionation. Dosimetric parameters to target &amp; organs at risk were analyzed. Toxicities including hematologic, dermatitis, pharyngitis &amp; other were monitored. Results: Of 71 patients, 70 patients were female and 1 is male. Majority (46%) of patients belonged to 46-55 years age group. Age ranged from 34 to 85 years. Mean age is 52 years. Clinical Stage IIIA was the most common stage with 29.5% patients followed by Stage IIB with 25.3% patients. Majority received adjuvant chemotherapy (52%). Mean treatment time is 21 days. All patients completed treatment without any major complications. Follow up ranged from 17 months to 27 months. Out of 71 patients, 1 patient expired on follow up after 4 months of radiation therapy due to non cancer related cause (Chronic pancreatitis). On follow up, 3 patients had distant metastasis alone (lung, bone metastasis, brain metastases) and 1 patient had both local disease and distant metastasis. 3 patients who progressed had stage IIIC disease &amp; 1 had stage IIIB disease. The V90 to the Planned Target volume (PTV) ranged from 90.4% to 99% to right sided disease, 90.3% to 96.5% to left sided disease. Heart V17Gy ranged from 1.27% to 12.5% &amp; heart V35Gy was 0.16% to 7.2%. Dermatitis was the most common adverse effect in this study. 31 patients (43.6%) developed fatigue during treatment. They continued their daily activities without any limitations. 35 patients (49.2%) had throat pain, of which 2 patients had it in 1st week, 21 patients had it in 2nd week and 12 patients had it in 3rd week. They were treated with non opioid analgesics. Shoulder pain was observed in 10 patients (14%) during treatment. Blood parameters were monitored weekly during treatment. No changes were observed. Conclusion: Hypofractionated post mastectomy radiation therapy is well tolerated in our study group. None of them developed any major acute reactions during and post treatment in the follow up period. Patients completed their treatment without any breaks during treatment. Respiratory motion management especially left sided disease patients should be used for achieving dose constraints.

Comparison of plan quality and robustness using VMAT and IMRT for breast cancer

Abstract To evaluate the plan quality and robustness of volumetric modulated arc therapy (VMAT) and intensity modulated radiation therapy (IMRT) for breast cancer, 50 patients, including 25 patients who received radiotherapy after breast-conserving surgery (BCR) and 25 patients who received postmastectomy radiotherapy (PRT), were selected for this study. Nominal VMAT and IMRT plans were generated for each patient on Eclipse treatment planning system (version 15.6). The dosimetric metrics, dose distribution, gamma passing rate, and delivery time were compared. In addition, 12 uncertainty plans with plan isocenter uncertainty and CT density uncertainty were recalculated based on the nominal plans for each patient. The dose volume histogram (DVH) band width (DVHBW) was adopted to quantify the plan robustness of the nominal plans for the perturbed scenarios in this study. For BCR, the dosimetric metrics except planning target volume (PTV) conformal index (CI) and ipsilateral lung V 5 were not statistically different for IMRT and VMAT plans. PTV CI of VMAT plans was better than that of IMRT plans (VMAT: 0.923 ± 0.024, IMRT: 0.855 ± 0.032, p = 0.003). The ipsilateral lung V 5 of VMAT plan was higher than that of IMRT plan (VMAT: 42.4% ± 2.8%, IMRT: 40.5% ± 4.0%, p = 0.045). The VMAT plans save more than 1.20 min compared to the IMRT plans (VMAT: 0.87 min, IMRT: 2.08 min, p &lt; 0.001). The gamma passing rates of VMAT plans were better than those of IMRT plans (3 mm/3%, VMAT: 99.7% ± 0.2%, IMRT: 99.4% ± 0.4%, p &lt; 0.001; 2 mm/2%, VMAT: 97.2% ± 1.0%, IMRT: 96.9% ± 0.6%, p = 0.108). For PRT, the dosimetric metrics of VMAT plans, including PTV D mean, homogeneity index (HI), CI, and D max of spinal cord, were significantly better than those of IMRT plans. The VMAT plans save more than 45% time compared with IMRT plans (VMAT: 1.54 min, IMRT: 2.81 min, p &lt; 0.001). The difference in gamma passing rates between VMAT plans and IMRT plans was not statistically significant. For the plan robustness, the DVHBW of VMAT plans and IMRT plans for BCR were 2.09% ± 0.23% and 2.98% ± 0.40%, respectively (p &lt; 0.05). For PRT, the DVHBW of VMAT plans was significantly better than those of IMRT plans (VMAT: 3.05% ± 0.26%, IMRT: 3.57% ± 0.27%, p &lt; 0.05). The results show that the dosimetric metrics of VMAT plans were comparable to those of IMRT plans. More importantly, the VMAT plans had excited dose distribution and fast execution efficiency. The plan robustness of VMAT plans were superior.

Complications After Prepectoral Versus Subpectoral Breast Reconstruction in Patients Receiving Postmastectomy Radiation Therapy: A Systematic Review and Meta-Analysis.

Outcomes of immediate breast reconstructions can be influenced by postoperative radiotherapy. However, there is no clarity on the use of prepectoral or subpectoral breast reconstruction in the setting of postmastectomy radiation therapy (PMRT). We reviewed evidence on the complication rates of prepectoral and subpectoral breast reconstruction in women undergoing PMRT. PubMed, Web of Science, and Embase databases were scanned for studies comparing complication rates of prepectoral and subpectoral breast reconstruction with PMRT. All complications were pooled in a random-effect meta-analysis to obtain odds ratio (OR). Eight observational studies were included. Meta-analysis showed no difference in the risk of infections (OR: 1.22 95% CI 0.79, 1.88 I2=0%), implant loss (OR: 0.86 95% CI 0.50, 1.50 I2=14%), seroma (OR: 1.01 95% CI 0.43, 2.34 I2=50%), hematoma (OR: 0.44 95% CI 0.12, 1.71 I2=0%), wound dehiscence (OR: 0.95 95% CI 0.42, 2.17 I2=0%), and skin necrosis (OR: 0.61 95% CI 0.21, 1.75 I2=36%), contracture (OR: 0.46 95% CI 0.15, 1.48 I2=54%) and the need for revision surgeries (OR: 0.85 95% CI 0.45, 1.60 I2=15%) between the prepectoral and subpectoral groups. Data from observational studies indicates that in appropriately selected patients there may not be any difference in the risk of early complications with prepectoral or subpectoral breast reconstruction with PMRT. Current evidence is limited by the small number of studies, short follow-up and selection bias. There is a need for randomized controlled trials comparing the two approaches to obtain robust evidence on long-term outcomes. This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Abstract PO3-22-04: PMRT Decision with low prediction of genomic test score in pT3N0M0 luminal breast cancer: Protocol MF22-02: International multicenter real-world data

Abstract Background: In current guidelines, there is no definite recommendation regarding postmastectomy radiation therapy (PMRT) in patients with luminal pT3N0M0 breast cancer (BC). The goal of this study is to determine whether PMRT could be safely omitted for a specific subgroup of those patients. Methods and Materials: There were 202 women from 16 centers with pT3N0M0 hormone receptor (HR) positive, Her2 neu (-) BC who underwent mastectomy, were analyzed retrospectively. None of the patients received neoadjuvant chemotherapy. Three patients were excluded because of positive surgical margins. The patients were divided into two groups, PMRT (+) (n=130) and PMRT (-) (n=69). Groups were compared in terms of overall survival, loco-regional recurrence rate, and distant metastases regarding Magee score (MS) (&amp;lt; 18 are considered low risk) (https://path.upmc.edu/onlineTools/mageeequations.html), menopausal status, axillary surgery, pathology, lymphovascular invasion (LVI), adjuvant chemotherapy, and adjuvant endocrine therapy. Results: The majority of the patients had invasive ductal carcinoma (49%, n=98). There was no significant difference regarding tumor size, axillary surgery, and adjuvant endocrine therapy between the two groups (p=0.82, p=0.28, p=0.12, respectively). LVI was 49% (n=98) and it was greater in PMRT (+) group (25% vs. 10%; p=0.01). PMRT (+) patients received more chemotherap(66% vs. 30%; p&amp;lt; 0.001), had more grade 3 tumors (28% vs. 9%, p=0.005), and more premenopausal (49% vs. 22%; p=0.0001). At a median follow-up of 51.3 months for the PMRT (-) group and 65.9 months for the PMRT (+) group (p=0.041), 9% (n=6) of patients from the PMRT (-) group and 2% (n=3) from the PMRT (+) group developed locoregional recurrence (LRR) (p=0.047). There was no difference in local recurrence (1% in PMRT (-) group vs. 2% in PMRT (+); p=0.7) and distant recurrence (7% in PMRT (-) group vs. 3% in PMRT (+); p=0.16) between patients who received PMRT and not had PMRT. Further comparison of the LRR in the PMRT (-) and PMRT (+) groups in patients with an MS &amp;lt; 18 did not show a significant difference (3% vs. 4%; p=0.64). However, among patients with a Magee score ≥18, the PMRT (-) group had a higher LRR rate compared to the PMRT (+) group (11% vs. 2%; p=0.01). In patients with an MS≥18, the administration of PMRT correlates with statistically significantly better LRR-free survival (HR 0.19; 95%CI 0.05 – 0.79; p=0.02). Conclusions: Our findings imply that when considering PMRT for BC with pT3N0M0, HR (+), and Her2 neu (-), clinicians can benefit from a combination of pathological risk factors and recurrence prediction models. Patients with MS&amp;lt; 18 receiving PMRT or not appear to experience a comparable rate of recurrence. Citation Format: Atilla Soran, Caleb King, Parul N. Barry, Rohit Bhargava, Hasan Karanlik, Melis Gultekin, Ferah Yiıdız, Aykut Soyder, Berk Goktepe, Kazim Senol, Caglar Guzel, Ebru Sen Oran, Levent Yeniay, Ahmet Dağ, Selman Emiroglu, Didem Can Trabulus, Alper Coskun, Neslihan Cabioglu, Hagigat Veliyeva, N. Zafer Utkan, Berkay Demirors, Efe Sezgin, John A. Vargo. PMRT Decision with low prediction of genomic test score in pT3N0M0 luminal breast cancer: Protocol MF22-02: International multicenter real-world data [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 PO3-22-04.

Abstract PO3-23-04: Patient-reported outcomes and complication profiles of implant-based breast reconstruction in patients with postmastectomy radiation therapy

Abstract Objective: This study aims to investigate the patient-reported outcomes (PROs) and complications of distinct implant-based breast reconstruction (IBBR) modality for patients with postmastectomy radiation therapy (PMRT). Methods: A retrospective review was conducted on breast cancer patients with stage II-III disease who performed IBBR following with PMRT between September 2016 and April 2022. The patients were categorized into two matched groups: (1) patients receiving prepectoral breast reconstruction (PBR) or subpectoral breast reconstruction (SBR) followed by PMRT; (2) patients undergoing PMRT with the tissue expander (PMRT-TE) or permanent implant (PMRT-PI) groups. PROs were measured with BREAST-Q questionnaire. Early and late complications were recorded and analysed. Results: A total of 55 eligible patients were recruited. For PROs, patients underwent PBR reported significantly higher Satisfaction with Breasts scores (P = 0.003) compared with SBR group, and PMRT-TE group presented higher Satisfaction with Breasts (P = 0.001) but lower Physical Well-being (P = 0.029) scores compared with PMRT-PI group. Moreover, Patients in SBR cohort had a higher risk of capsular contracture (Baker grade III or IV) (20.5% vs 6.3%) and implant dislocation (48.7% vs 12.5%) than patients in PBR cohort. Patients in PMRT-PI group had a slightly higher rate of capsular contracture (Baker grade III or IV) than PMRT-TE group (20.8% vs 12.9%). Conclusions: PBR was associated with lower rates of late complications, especially for implant dislocation, and higher Satisfaction with Breasts scores compared to SBR. In addition, compared to PMRT-TE with PMRT-PI, patients in PMRT-TE cohort reported superior patient-reported outcomes of Satisfaction with Breasts. Table 1. Patient and Tumor Characteristics of 55 Patients Stratified with Prepectoral/Subpectoral and PMRT-TE/PMRT-PI Reconstructive Procedure. XX- XX Table 2. Patient-Reported BREAST-Q Scores XX- XX Table 3. Association of Reconstruction Techniques with Late Complications. XX- XX Citation Format: Jian Liu, Cong Chen, Honggang Chen, Aizhai Xiang, Ruzhen Zheng, Shufang Hu, Jufeng Guo, Li Qu, Jun Zhou, Jiong Wu. Patient-reported outcomes and complication profiles of implant-based breast reconstruction in patients with postmastectomy 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 PO3-23-04.

Abstract PO5-19-02: I-PREPARE: International Prospective REgistry on Pre-pectorAl breast Reconstruction (EUBREAST 11R-NCT 05817175)

Abstract Background: Despite the progressive de-escalation of breast cancer (BC) surgery, mastectomy rates remain around 30-40%. Furthermore, up to 1/3 of BC patients undergo a contralateral risk-reducing mastectomy and around 40% of mutation carriers choose a bilateral intervention. To date, immediate breast reconstruction (IBR) with implants is the most commonly performed reconstructive procedure. After an initial experience with implants in subcutaneous positioning under the mastectomy flap in the seventies, this technique was abandoned due to a high rate of implant loss (28%), flap necrosis (13.5%) and capsular contracture (56%). For this reason, the positioning of the implant under the pectoralis major has become the standard of care. However, over time surgical techniques and implants have improved, resulting in decreasing implant loss, flap necrosis and capsular contracture rates. Moreover, biological/synthetic meshes have been used to cover the implant placed over the pectoralis major, thus avoiding to mobilize the muscle with some benefits in terms of reduced complications (no animation deformity, no chronic pain, no loss of muscular function), patients’ wellbeing, postoperative pain and recovery. Additionally, recent literature reported encouraging results with polyurethane breast implants in pre-pectoral positioning without any kind of implant coverage. Although these procedures are considered safe they were not evaluated in prospective randomized trials. In 2019 a joint consensus on pre-pectoral breast reconstruction (PBR) clearly recommended to properly audit the results in terms of surgical complications and patient-reported outcomes. Based on these premises the EUBREAST (European Breast Cancer Research Association of Surgical Trialists, www.eubreast.org) study group decided to launch a prospective international cohort study aimed at comparatively evaluating data on different surgical techniques of PBR with or without PMRT. Therefore, we will prospectively evaluate the utilization of PBR, including surgical, oncological, aesthetic and patients’ satisfaction and quality of life outcomes related to each type of surgical technique and the interaction with post-mastectomy radiation therapy (PMRT). Eligibility criteria: - Female patients age≥18 years - Signed informed consent - Patients undergoing mono/bilateral therapeutic mastectomy and immediate PBR Exclusion criteria - Patients not suitable for surgical treatment - Patients undergoing subpectoral reconstruction, reconstruction with tissue expander or autologous IBR Specific aims: The primary endpoint is implant-loss at 3 months defined as the unplanned removal or loss of the implant, as a result of infection or any other complication Secondary endpoints are infection, re-admission and re-operation rates, quality of life evaluated through BREASTQ Breast Reconstruction Module and EQ-5D-5L questionnaires on an App for patients before and after breast reconstruction at 6, 12, 24 months, early onset complication at 3 months, late-onset complications at 6, 12, 24 months, further surgery at 24 months, time to adjuvant therapy. Tertiary endpoints are further surgery, loco-regional recurrence, disease free survival, breast cancer specific survival, distant-disease free survival, overall survival, development of seroma/breast implant-associated anaplastic cell lymphoma. Statistics: We will use a single-arm design to assess the surgical safety of PBR through implant loss rate at 3 months which is expected to be ≤9% based on previous literature; 12% or greater will be regarded as unacceptably high. The assessment will be based on 1,112 patients. For this sample size calculation, power was set to 90%, and the two-sided alpha was set to 0.05. Allowing for a 10% loss to follow-up at 3 months, we aim at recruiting 1,236 patients. Accrual has not started yet. Funding: EUBREAST ETS Italy Contact: Oreste Davide Gentilini: gentilini@eubreast.org Citation Format: Rosa Di Micco, Maggie Banys-Paluchowski, Maria-Joao Cardoso, Jana de Boniface, Bahadir M. Gulluoglu, Orit Kaidar-Person, Thorsten Kühn, Maurizio Bruno Nava, Philip Poortmans, Shelley Potter, Nicole Rotmensz, Tanja Spanic, Marc Thill, Luzia Travado, Walter Weber, Oreste Davide Gentilini. I-PREPARE: International Prospective REgistry on Pre-pectorAl breast Reconstruction (EUBREAST 11R-NCT 05817175) [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 PO5-19-02.

Abstract PO3-23-05: Capsular contracture after post-mastectomy radiotherapy in the patients undergoing implant-based breast reconstruction: impact of implant positioning and two-stage surgery

Abstract Background Capsular contracture is a significant concern in patients undergoing post-mastectomy radiotherapy (PMRT) following implant-based breast reconstruction. It negatively impacts cosmetic outcomes and can have a profound effect on the individual's quality of life. Our study aimed to explore whether the degree of capsular contracture varies based on the placement of the inserted implant and the type of operation (one- or two-staged). Patients and Methods This retrospective study was conducted at a single center, Ganganm Severance Hospital, Yonsei University College of Medicine, Seoul, South Korea. Our study included patients who underwent PMRT following total mastectomy and implant-based breast reconstruction surgery between January 2017 and September 2022. To assess the degree of capsular contracture, we evaluated the presence of capsular contracture, particularly severe capsular contracture classified as Baker grade 3 or higher, as well as implant migration. The implants were placed either in the pre-or sub-pectoral position, and the surgical approach employed was either direct-to-implant (DTI) or two-staged operation. Results A total of 195 patients were included in the study, with 83 (42.6%) patients in the pre-pectoral group and 112 (57.4%) patients in the sub-pectoral group. In addition, 116 underwent a two-stage operation, while 79 underwent DTI surgery. There was a significant difference in the occurrence of capsular contracture based on the implant placement, with 16 patients (19.3%) in the pre-pectoral group and 46 patients (41.1%) in the sub-pectoral group experiencing this complication (OR 4.142 [1.973-8.698]). Furthermore, the severity of capsular contracture differed significantly between the two groups, with 5 patients (6.0%) in the pre-pectoral group and 16 patients (14.3%) in the sub-pectoral group affected (OR 3.434 [1.153-10.227]). The incidence of capsular contracture was lower in the two-stage operation group compared to the DTI group (28 [23.9%] vs 34 [38.6%]; OR 3.064 [1.528-6.141]), and the severity of capsular contracture was also reduced (9 [7.7%] vs 12 [14.5%]; OR 2.854 [1.092-7.455]). There were no significant differences in other complications such as seroma and infection. In addition, sub-pectoral placement was identified as a significant risk factor for implant upward migration (OR 2.531 [95% CI, 1.263-5.071]). Conclusions Our findings suggest that pre-pectoral reconstruction and the two-stage operation are beneficial for patients who may undergo PMRT based on their initial nodal stage. These approaches can help reduce the incidence of capsular contracture and abnormal implant migration following radiation, leading to improved aesthetic outcomes and greater patient satisfaction. Citation Format: Sohyun Moon, Kyunghyun Min, Jung Hwan Eom, Yoonwon Kook, Seung Ho Baek, Junghyun Kim, Min Ji Kim, Seung Eun Lee, In Sik Yun, Tai Suk Roh, Soong June Bae, Joon Jeong, Young Seok Kim, Sung Gwe Ahn. Capsular contracture after post-mastectomy radiotherapy in the patients undergoing implant-based breast reconstruction: impact of implant positioning and two-stage surgery [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 PO3-23-05.

Abstract PO2-03-06: Pathological complete response with chemotherapy and immune checkpoint inhibition in triple negative inflammatory breast cancer (TN-IBC)

Abstract BACKGROUND: Patients with stage III inflammatory breast cancer (IBC) are treated with tri-modality therapy consisting of neoadjuvant systemic therapy followed by modified radical mastectomy and post-mastectomy radiation therapy. Triple negative IBC (TN-IBC) is the subtype of IBC associated with the worst survival outcomes. Pathological complete response (pCR) rates after neoadjuvant chemotherapy have been historically low, with reports ranging between 13% and 42%. It is unknown if the addition of immune checkpoint inhibition to chemotherapy leads to improved pCR rate in TN-IBC as these patients were underrepresented in the seminal studies that led to the approval of chemoimmunotherapy for high-risk early-stage triple negative breast cancer (TNBC). METHODS: We conducted a retrospective analysis of patients with stage III TN-IBC who underwent breast surgery after receiving neoadjuvant chemoimmunotherapy. Patients were seen at Dana-Farber Cancer Institute (DFCI) or MD Anderson Cancer Center (MDACC). The analysis population consisted of all patients that were seen at either institution no more than 30 days after starting immunotherapy. The primary objective was the estimation of the pCR rate. An additional cohort of patients with TN-IBC treated with neoadjuvant chemotherapy and pembrolizumab while participating in the multi-institutional PELICAN trial (NCT03515798) will be added to the analysis at the time of the meeting. RESULTS: Thirty-seven patients (16 DFCI, 21 MDACC) were identified as having stage III TN-IBC and having received neoadjuvant chemoimmunotherapy. Twenty-five patients met criteria for inclusion in the analysis population. Patients in the DFCI cohort initiated treatment with chemoimmunotherapy between May 2021 and June 2022, and in the MDACC cohort between June 2021 and October 2022. Most patients were White (N=20, 80%), premenopausal (N=15, 60%) and overweight/obese (N=19, 76%). All patients received pembrolizumab-based therapy (Table 1). Among the 25 patients in the analysis population, 10 (40%) (95% CI: 21% to 61%) achieved a pCR, 6 patients experienced RCB-II and 9 RCB-III. At the time of last follow up, 84% of patients were alive. The results will be updated at the time of the meeting to include an additional cohort of 17 patients from the PELICAN trial. CONCLUSIONS: The addition of immune checkpoint inhibition to neoadjuvant chemotherapy led to a higher pCR rate in TN-IBC than most historical estimates. However this is still lower than what has been reported in TNBC in general. The investigation of novel systemic therapies is warranted in TN-IBC. Table 1. Patient characteristics and treatment received (analysis population) Citation Format: Filipa Lynce, Samuel Niman, Anthony Gonçalves, Megumi Kai, Sean Ryan, Elizabeth Troll, Rachel Layman, Antonio Giordano, Azadeh Nasrazadani, Faina Nakhlis, Jennifer Bellon, Laura Warren, Caroline Block, Susan Schumer, Anthony Lucci, Savitri Krishnamurthy, Florence Lerebours, Florence Dalenc, Christelle Levy, Thierry Petit, Marianne Leheurteur, Thomas Bachelot, Olivier Trédan, Sylvain Ladoire, Leonor Lopez Almeida, Christophe Zemmour, Sara Tolaney, Vicente Valero, François BERTUCCI, Meredith Regan, Wendy Woodward. Pathological complete response with chemotherapy and immune checkpoint inhibition in triple negative inflammatory breast cancer (TN-IBC) [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 PO2-03-06.