Excellent Response to 177Lu-DOTATATE Peptide Receptor Radionuclide Therapy in a Patient with Treatment-Related Neuroendocrine Prostate Cancer with Urinary Retention and Rectal Obstruction: A Case Report.

Treatment-related neuroendocrine prostate cancer (tNEPC) occurs after androgen deprivation therapy and has a poor prognosis; however, there are few effective treatments for tNEPC. Therefore, tNEPC management is often challenging. This is a case of a 65-year-old Asian male patient with prostate adenocarcinoma who had metastases at initial presentation. After prostate biopsy revealed neuroendocrine prostate cancer (NEPC), he was treated with platinum-based systemic chemotherapy followed by pembrolizumab treatment. The primary tumor regions temporarily regressed, but progression of the primary tumor resulted in urinary retention and rectal obstruction; therefore, a transverse colostomy was performed, and a urethral catheter was inserted. Following somatostatin receptor scintigraphy (SRS), it was determined that the primary tumor expressed somatostatin receptors. Based on these results, treatment with 177Lu-DODATATE peptide receptor radionuclide therapy was prescribed. Subsequently, the primary tumor regressed remarkably, and the urethral catheter was removed. 177Lu-DOTATATE peptide receptor radionuclide therapy may be an effective option for tNEPC, which has few effective treatment options.