Introduction: Male breast cancer (MBC) is a rare malignancy, accounting for less than 1% of all breast cancers (BC). Evidence guiding its management is largely extrapolated from female BC, although MBC has distinct clinicopathological features that warrant dedicated description in local settings.
Methods: A descriptive retrospective observational study was conducted of men with BC treated surgically at the Hospital Clínico UC CHRISTUS. Clinical presentation, histopathology, treatment patterns, germline testing and follow-up outcomes were described.
Results: Sixteen patients treated between 2008 and 2025 were included. Median age at presentation was 74 years (range 50–84), and all patients presented with a palpable breast mass. Most tumours were invasive (87.5%) and predominantly invasive ductal carcinoma (81.2%). Hormone receptor (HR) positivity was observed in 15 cases, and HER2 amplification was identified in only one patient. Median tumour size was 19 mm (range 5–42). Mastectomy was performed in 93.8% of patients, and sentinel lymph node biopsy in 62.5%; 25.0% had pathologically positive axillary nodes. Neoadjuvant therapy was administered in 31.2% of patients, most commonly chemotherapy. Adjuvant endocrine therapy was the most frequently used systemic treatment (75.0%), followed by chemotherapy (37.5%) and radiotherapy (31.2%). Germline testing was performed in 6 of 16 patients, identifying two breast cancer gene 2 pathogenic variants. During follow-up, three patients died, one due to BC progression and two from non-oncologic causes.
Discussion: This series represents the largest published Chilean cohort of MBC to date. Findings are consistent with a predominantly invasive ductal, HR-positive profile and with contemporary treatment patterns in which mastectomy, axillary staging and adjuvant endocrine therapy are commonly used. Because of the limited sample size and low number of events, outcome findings should be interpreted descriptively. Improved access to standardised biomarker evaluation and genetic testing may help refine care in this uncommon disease.
