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INTRODUCTION Extreme hypofractionation in patients with early-stage breast cancer has been studied in randomized phase III non-inferiority trials. There is scarce data on this strategy in Latin American patients. OBJECTIVES To describe the profile of patients diagnosed with breast cancer treated with radiotherapy with an ultra-hypofractionated regimen (5 fractions of 5.2 Gy, in one week), as well as the dosimetric aspects and acute toxicity related to the treatment. METHOD Retrospective cohort through a Brazilian uni-institutional series, with analysis of pathological, dosimetric, and toxicity variables. RESULTS Between May 2020 and March 2022, 67 patients were included, with a median age at diagnosis of 71 years (41-93). Regarding staging, 25.8% had in situ tumors, 60.6% of patients were IA, and only 3% were stage IIA. Nineteen percent of patients had histological grade 3; 24.6%, had nuclear grade 3. Hormone receptors were positive in 92.1% of patients. The mean ki67 was 19%, and HER2 was negative at 84.5%. All patients underwent conservative surgery, and 5 underwent reconstruction with autologous flaps. Fifty-one patients underwent hormone therapy and only 2 underwent adjuvant chemotherapy. All but two patients were treated with the conformal technique (VMAT was used due to unfavorable anatomy). The mean volume of the irradiated breast was 926 cm3 (ranging from 920 to 932 cm3). Regarding the constraints of the organs at risk, the average V8Gy of the ipsilateral lung was 11.4%, ranging from 0 to 24%. In the heart, the average volumes receiving 1.5Gy and 7Gy were, respectively, 9.2% and 0.7%. No patient had acute toxicity greater than grade 2. The effects on the skin appeared on average 20 days after the end of treatment, with resolution in a maximum of 3 months. The median follow-up time was 10 months (3 - 26). We did not observe any case of local-recurrence, of breast-cancer-related death. CONCLUSION Although our follow-up time is premature, we have found that ultra-hypofractionated radiotherapy was feasible, tolerable, and safe, for patients with early breast cancer. Also, the constraints on the organs at risk were respected. There were no high-grade acute toxicities. Besides convenience, ultra-hypofractionation can improve access to radiotherapy in resource-scarce settings. Citation Format: Leticia Hernandes de Brito, Felipe Cicci Farinha Restini, Maria Thereza Mansur Starling, Gabriela Silva Moreira de Siqueira, Gustavo Nader Marta, Heloisa de Andrade Carvalho, Samir Abdallah Hanna. Ultra-hypofractionated Radiotherapy for Breast Cancer: A Brazilian Single-Institutional Series [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P1-10-03.

IntroductionMale breast cancer (MBC) is uncommon tumor that represents only 0,5% of all tumor diagnoses in men. In general, the age of incidence of MBC is, on average, 5-10 years later than women and have more advanced stage at diagnosis and worse prognosis. International recommendations for staging and treatment for MBC are the same as female breast cancer. Due to the rarity of the tumor, few data are available related to MBC. The aim of this study was to evaluate the clinicopathological characteristics, treatment trends and survival outcomes in MBC in Sao Paulo State of Brazil.MethodsThis population-based study had included men diagnosed with invasive breast cancer between January 2000 and June 2020 from Fundação Oncocentro de Sao Paulo. Patients were described according to age, education level, treatment modalities and medical practice. Categorical variables are described as percentages and frequencies. The association between demographic and treatment factors and overall survival was evaluated using a Cox Proportional Hazard (PH) regression model while accounting for different lengths of participant follow-up. Uni- and multivariable Cox proportional-hazards model were used to estimate hazard ratios with corresponding 95% confidence intervals for OS. The Kaplan-Meier (KM) curves were used to visually display survival curves, and the log-rank test were used to compare the estimated KM curves. ResultsA total of 907 MBC patients were included (825 patients had invasive ductal carcinoma; 64, had invasive lobular carcinoma;18, had especial subtypes). The age at diagnosis were 70y in 12.2%, 51.5% and 27.1% of patients, respectively. The proportion of stage I, II, III and IV were 19.5%, 36.6%, 31,5% and 12.3%, respectively (Table 1). OS by stage at diagnosis was presented in the Figure 1. For each stage I, II, III and IV, 5- and 10-years OS were, respectively, 87.9% and 77.8%, 79.9% and 58.9%, 51.6% and 24.5%, 20.0% and 5.6%. In the multivariable analyses adjusted for practice (public or private), education (low or medium/high), age, stage at diagnosis and treatment. modalities, the significant independent predictor for OS was stage at diagnosis only Figure 2. ConclusionMBC tends to be diagnosed at a more advanced stage and older age at the time of diagnosis. Type of practice, age, treatment modalities and educational level did not influence survival outcomes. Stage at diagnosis was the most important factor related to the OS. Citation Format: Ridânia de Oliveira Frederice, Allan AndressonLima Pereira, Felipe EduardoMartins de Andrade, Samir Abdallah Hanna, Heloisa de Andrade Carvalho, Gustavo Nader Marta. Characteristics and survival outcomes of male breast cancer in Sao Paulo state of Brazil: A population-based study [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P3-12-27.

Background: Recent medical literature reports that mastectomy rates are increasing in early breast cancer. The reasons for this have not yet been elucidated and appear to be complex and can be related to: availability of immediate reconstruction, expertise of the surgeon, increment of genetic tests and beliefs, unwillingness or impossibility of receipting radiotherapy, and information of the patients themselves. The present study aimed to demonstrate mastectomy rates throughout the years from a single Brazilian institution and to correlate it with age, neoadjuvant therapies and tumor staging. Methods: A retrospective analysis of breast cancer surgeries from patients treated at Hospital Sírio-Libanês cancer center from 2005 to 2018 was performed. The institutional database electronically of physically registered in this period included pathology, radiology, and clinical information. Chi-squared coefficient of correlation was applied for categorical variables analysis of association, and for significant findings a multivariate regression analysis was performed. All statistical analyses were performed in STATA version 15.1C. Results: Medical records from 2,942 patients treated were analyzed. 1,798 mastectomies (including nipple-sparing mastectomies and skin-sparing mastectomies) were performed against 1,144 conservative surgeries (61.11% x 38.89%). The range of mastectomy rates varied from 73.04% (2007) to 48.8% (2018) and mastectomy rates showed a slight decrease (53.84% in 2005 and 48.14% in 2018). Type of surgery (conservative, mastectomy, skin-sparing mastectomy) was associated with neoadjuvant treatment (p Conclusions: These results demonstrate that our mastectomy rates, differently from global trends, did not increase through the past 15 years. These findings are probably related to impossibility of genetic tests in this population, accurate diagnostic techniques and the achievement of higher response rates with neoadjuvant treatment. Interestingly, breast-conserving surgery rates were inversely correlated with older age, which can reflect an individualized therapeutic approach among a subgroup of patients potentially vulnerable to chemo-related toxicity. Citation Format: Thatyane EspósitoGallo Cunha, Thamyse FernandaSá Dassie, Julianne MariaSilva Lima, Max Senna Mano, Lincon Jo Mori, Samir Abdallah Hanna, Sandro ViniciusMachado Melo, Gustavo Nader Marta, Felipe EduardoMartins Andrade. Mastectomy rates in a single Brazilian institution through the past 15 years: Are we following the global trend? [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P1-20-29.