Male Breast Cancer After Finasteride Therapy for Benign Prostate Hyperplasia

The document reports a case of male breast cancer (MBC) in a 59-year-old man who had been undergoing finasteride therapy for benign prostate hyperplasia (BPH) for four years. The patient discovered a palpable mass in his left breast, which was later diagnosed as invasive ductal carcinoma through ultrasound-guided core biopsy. Following the diagnosis, the patient underwent a simple mastectomy and was treated with adjuvant chemotherapy using tamoxifen. The case highlights the rare but possible side effect of MBC associated with finasteride therapy, a medication commonly used to treat BPH and androgenetic alopecia by inhibiting the conversion of testosterone to dihydrotestosterone. The document suggests that patients on finasteride therapy should be educated about self-examination of breasts and that physicians should conduct further studies in patients presenting symptoms of breast cancer. The incidence of MBC in the study mentioned, which included 3047 men, was higher than that in the general population, with 3 cases in the finasteride group and 1 in the combination group with doxazosin.