Male Breast Cancer in Portugal: A Descriptive Analysis of a 20-Year Cohort.

Objective: Male breast cancer (MBC) is a rare malignancy, representing less than 1% of all breast cancer cases. Despite the rising incidence, MBC research remains limited, with most data extrapolated from female breast cancer (FBC). This study evaluated the clinicopathological features, treatment strategies, and survival outcomes of MBC patients in Portugal over two decades. Materials and Methods: A retrospective analysis of MBC cases from the Portuguese National Oncology registry (2001-2021) was conducted. Clinicopathological features, therapeutic strategies, and overall survival (OS) were assessed across three disease categories: localized, locally advanced, and metastatic. Hormone receptor status, human epidermal growth factor receptor 2 (HER2) expression, and Ki-67 index were recorded, and survival was estimated using Kaplan-Meier methods. Results: A total of 620 MBC cases were included with median age at diagnosis 68 years (interquartile range: 60-77). Localized disease accounted for 60.3% of the cases, locally advanced for 24.5%, and metastatic 15.2%. Most tumours were invasive carcinoma of no special type (86%), and hormone receptor-positive (estrogen receptor: 96.6%; progesterone receptor: 85.6%). HER2 -disease was noted in 11.6% of cases and triple-negative in 1.6%. Mastectomy was the primary surgical intervention while tamoxifen was the most widely used adjuvant endocrine therapy-exemestane therapy (A-ET). ET was the most prescribed first-line therapy. Median OS was 86 months for localized, 70 months for locally advanced, and 41 months for metastatic disease. Conclusion: This study highlights the unique challenges of MBC, including late-stage diagnoses and reliance on FBC-derived protocols. Findings suggest an urgent need for male-specific clinical trials and molecular research to optimise treatment and outcome. In Portugal increased awareness and early detection initiatives will be important to advance MBC care.