Case report: metachronous male metastatic breast and colon cancer in a BRCA2 mutation carrier

Male breast cancer (MBC) is rare and typically diagnosed at later stages, often in older men. Pathogenic BRCA2 mutations are implicated in a significant proportion of MBC cases and may confer increased risk for other cancers. A 66-year-old male presented with right upper limb edema and back soreness. Imaging and biopsy confirmed stage IV invasive ductal carcinoma, Luminal B HER2-negative. Genetic testing revealed a germline BRCA2 mutation. During routine imaging, a second primary colon cancer was discovered and resected. MBC represents less than 1% of all male cancers and is frequently associated with delayed diagnosis. BRCA2 mutations significantly increase the risk for male breast and gastrointestinal cancers. This patient underwent endocrine and CDK4/6 inhibitor therapy and followed by surgery and adjuvant chemotherapy for the colon carcinoma. Disease remained stable on follow-up. This case highlights the importance of genetic testing, vigilance for second primary malignancies in BRCA2 carriers, and the value of multidisciplinary care for MBC patients. The co-occurrence of these malignancies in a male BRCA2 carrier is rare and underscores the need for broader surveillance in such patients.