Abstract P3-12-27: Characteristics and survival outcomes of male breast cancer in Sao Paulo state of Brazil: A population-based study

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.