Radiation‐induced sarcoma after radiation therapy for prostate adenocarcinoma

INTRODUCTION: Radiation therapy is widely used for prostate cancer, but radiation‐induced sarcomas have been rarely reported. CASE PRESENTATION: A 77‐year‐old Japanese male was diagnosed with prostate cancer and received a combined androgen blockade and radiation therapy (total dose of 76 Gy). Five years after the radiation therapy, testicular pain and dysuria appeared. Computed tomography showed a soft tissue dense mass with invasion to the right subpubic ramus and prostate, mainly to the perineum. A needle biopsy revealed the pathological features of high‐grade sarcoma. The patient was diagnosed with radiation‐induced sarcoma based on the cancer's occurrence in the vicinity of the radiation field. CONCLUSION: Although irradiation is one of the important treatments for prostate cancer, the risk of radiation‐induced malignancy should be considered.