Abstract
INTRODUCTION: Testosterone replacement therapy (TRT) can improve quality of life for men with hypogonadism. However, it is generally avoided in patients with a history of prostate cancer or breast cancer as there is uncertainty about risks. This case illustrates an example of synchronous metastatic prostate cancer and male breast cancer following TRT. PRESENTATION OF CASE: A 72-year-old man with previously treated intermediate-risk prostate adenocarcinoma experienced a gradual rise in prostate-specific antigen (PSA) while self-administering testosterone replacement. He was later found to have recurrent metastatic prostate cancer and prior to initiating androgen deprivation therapy (ADT), he was also diagnosed with male breast cancer. His treatment has consisted of continued ADT for metastatic castration-sensitive prostate cancer (mCSPC) as well as surgical resection of his breast cancer. DISCUSSION: ADT plays a role in treatment of male breast cancer and prostate cancer. TRT remains relatively contraindicated in patients with a history of these malignancies, but the evidence supporting this recommendation is somewhat limited. CONCLUSION: This case highlights the potential risk for synchronous recurrent prostate and new male breast cancer following TRT. Further studies are needed to better elucidate the increased risks of these malignancies with TRT.