Assessment of Prognostic and Therapeutic Factors in Male Breast Cancer: An Observational Study of a Southwest Spanish Single Center

Background: Male breast cancer (MBC) accounts for less than 1% of breast cancer, requiring extrapolation of results from studies in women. The aim of the study is to evaluate prognostic and therapeutic factors with special focus in endocrine treatment (ET) on the disease outcome.Methods: Observational, retrospective, single-center study of 53 MBC treated between January 1997 and December 2018 participated in the study. Among the participants, 48 patients had a performance status (PS) 0-1 (91%), 48 were hormone-receptor-positive (91%) and 4 were human epidermal growth factor 2 receptor (HER2) positive (8%). A total of 45 patients (85%) were treated with ET, with 36 patients (68%) receiving treatment in an adjuvant setting. The association analysis was performed using Chi-square test and survival was estimated using Kaplan-Meier with SPSS v25. Results: The cohort had a median age of 68 years old (range: 40-88). We found that 84% had a non-metastatic breast cancer. A breast cancer gene (BRCA) analysis was carried out in 43% of the patients, showing BRCA2 mutated in 26.1% of those analyzed, without obtaining a benefit in overall survival (P=0.698). The analysis showed higher 5-year overall survival (OS) for PS 0 (P=0.010), absence of vascular invasion (P=0.033), Ki67 ?14% (P=0.041) and absence of metastasis at diagnosis (p<0.0001). Patients receiving adjuvant ET above 5 years had a longer median OS (89 vs 69.6 months, P=0.024), disease-free survival (DFS), and distant relapse (84 vs 48 months; P=0.005, and P=0.002, respectively).Conclusions: Several prognostic factors for male breast cancer have been described. Noteworthy, patients receiving adjuvant ET above 5 years had a higher OS and DFS. BRCA did not show prognostic value in OS in this cohort. Further studies with larger sample size are necessary.