Treatment‐related neuroendocrine prostate cancer with BRCA2 germline mutation treated with olaparib

Introduction The efficacy of olaparib for treatment‐related neuroendocrine prostate cancer is unknown. Here, we report a case of treatment‐related neuroendocrine prostate cancer with a BRCA2 mutation that was treated with olaparib with 1‐year efficacy. Case presentation A 75‐year‐old man initially diagnosed with prostate adenocarcinoma developed treatment‐related neuroendocrine prostate cancer after 10‐year androgen deprivation therapy. Despite the initial temporary effects of etoposide and carboplatin, the patient experienced prostate bed tumor recurrence 1 year after chemotherapy cessation. FoundationOne® detected a BRCA2 gene mutation, and olaparib was initiated after repeating one chemotherapy course using the same chemotherapeutic agents. The patient received olaparib with sustained tumor regression for 1 year without severe side effects. Conclusion Olaparib may be the treatment of choice for treatment‐related neuroendocrine prostate cancer in patients with BRCA mutations.