HER2 Type Male Breast Cancer Successfully Treated with Pertuzumab, Trastuzumab, and Eribulin Therapy: A Case Report

Background: Male breast cancer is rare, accounting for approximately 0.5% - 1.0% of all breast cancer cases; hormone-dependent luminal type male breast cancer is the most common. The proportion of hormone receptor-negative and human epithelial growth factor Receptor type 2-positive breast cancer is extremely low among male breast cancer. A patient with advanced HER2 type breast cancer, a rare male breast cancer, was successfully treated with pertuzumab, trastuzumab, and eribulin therapy. Case Presentation: A 75- year-old man presented to our hospital with induration of the right anterior chest and lymphoedema of the right upper limb. Based on the results of core needle biopsy, he was diagnosed with HER2 type invasive ductal carcinoma associated with bone metastasis (stage IV). Chemotherapy with pertuzumab, trastuzumab, and eribulin was started. The drugs were remarkably effective, and his lymphoedema tended to improve. Conclusion: We reported a successful case of chemotherapy and targeted therapy for a rare male breast cancer of HER2 positive and hormone negative type.