A retrospective study of post-radiation sarcoma from three institutions in Japan with a review of the literature.

This study investigated incidence, clinical characteristics, and outcomes of post-radiation sarcoma, a rare but severe complication following radiotherapy. Post-radiation sarcoma is a malignant tumor arising within irradiated areas after a latency period, histologically different from the primary tumor. We retrospectively analyzed cases from January 2000 to January 2025 at three institutions in Japan, employing widely accepted diagnostic criteria. Patient characteristics, treatment details, oncologic outcomes, and prognostic factors were evaluated. Our study included 14 patients with various primary cancers, including three breast cancers, three prostate cancers, and one each of other cancer types. Among the cases, six had osteosarcoma, six had undifferentiated pleomorphic sarcoma, one had chondrosarcoma, and one had malignant peripheral nerve sheath tumor, predominantly occurring in the trunk. The median latency period from last irradiation to diagnosis was 9.9 years (range, 3.0-19.5 years). The median total radiation dose administered before post-radiation sarcoma diagnosis was 52.5 Gy (range, 12-74 Gy). The median overall survival and probability of 5-year overall survival were 2.6 years and 46.8%, respectively. The only factor that tended to correlate with prognosis was whether complete resection was achieved (P = 0.09). A literature review confirmed an increasing number of post-radiation sarcoma cases following radiotherapy for prostate cancer in recent years. The incidence of post-radiation sarcoma is expected to rise alongside the number of patients undergoing radiotherapy. Early detection and appropriate treatment are essential to improve prognosis, highlighting the need for careful long-term monitoring of patients receiving radiotherapy for post-radiation sarcoma.