Radiation-Induced Leiomyosarcoma in Prostate After Brachytherapy for Prostatic Adenocarcinoma

Abstract Radiation (RTx) has been employed as a curative therapy for prostatic adenocarcinoma. RTx-induced sarcomas are rare late adverse event, representing less than 0.2% of all irradiated patients. RTx-induced sarcomas are more aggressive tumors than prostatic adenocarcinoma. Herein, we present a case with RTx-induced prostatic leiomyosarcoma after permanent brachytherapy for prostatic adenocarcinoma. A 69-year-old male was diagnosed as localized prostatic adenocarcinoma, and treated by brachytherapy. Dysuria and gross hematuria started to appear six years after brachytherapy. Urethroscopy showed stenosis by a tumor at the prostate. Transurethral prostatectomy was performed for a diagnosis. Based on pathological findings, we diagnosed as leiomyosarcoma of prostate. He was treated with three cycles of neo-adjuvant chemotherapy (CT) consisted with doxorubicin and ifosfamide (AI), and then performed prostatocystectomy with intrapelvic lymphadenectomy. The tumor extended from the prostate and infiltrated the bladder wall and serosa with lymphatic and venous invasion. The surgical margin was negative, and no residual prostatic adenocarcinoma was observed. The proportion of necrotic tumor cells by neo-adjuvant CT was less than 50%. Subsequently, adjuvant CT was offered, but he chose a follow-up without CT. Local recurrence and lung metastasis were detected by computed tomography three months after the surgery. He was treated again with AI. However, CT was not effective and he died six months after the operation. In conclusion, effective treatment strategy for prostatic sarcoma should be developed in the near future, although the clinical feature of prostatic sarcoma remains unclear due to rare incidence.