Characteristics and Survival Outcomes of Male Breast Cancer in Brazil: A Large Population-Based Study

Abstract

Aims: This study evaluated the clinicopathological characteristics, treatment trends, and overall survival (OS) in male breast cancer (BC) in Sao Paulo State of Brazil.

Materials and methods: Men diagnosed with invasive breast cancer between January 2000 and June 2020 were identified from Fundação Oncocentro de Sao Paulo database encompasses data pertinent to 46 million residents of the Sao Paulo State of Brazil. Patients were described according to age, education level, clinical stage, treatment modalities, and medical practice. Categorical variables were described as percentages and frequencies. Demographic, treatment factors, and OS were associated using a Cox proportional hazard regression model while accounting for different lengths of participant follow-up. The Kaplan-Meier curves were used to display survival curves.

Results: A total of 907 male BC patients were included. The age distribution at diagnosis was <51 years, 51-70 years, and >70 years in 21.5%, 51.5% and 27.0% of patients, respectively. The proportions of stages I, II, III, and IV were 19.5%, 36.6%, 31.5%, and 12.3%. For each stage I, II, III, and IV, 5- and 10-years OS were 87.9% and 77.8%, 79.9% and 58.9%, 51.6% and 24.5%, 20.0% and 5.6%, respectively. Patients who received postoperative radiotherapy experienced a significant improvement in OS (HR 0.67; 95% CI 0.53-0.84; p < 0.001). In the multivariable analysis 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.

Conclusion: Male BC tends to be diagnosed at a more advanced stage and older age at the time of diagnosis. Age and educational level did not influence survival outcomes. Stage at diagnosis and the use of postoperative radiotherapy were factors associated with improved OS.

Keywords: Epidemiology; Male breast cancer; Prognosis; Rare disease; Survival.