Post-radiation sarcoma: A study by the Eastern Asian Musculoskeletal Oncology Group.

The oncologic risk of ionizing radiation is widely known. Sarcomas developing after radiotherapy have been reported, and they are a growing problem because rapid advancements in cancer management and screening have increased the number of long-term survivors. Although many patients have undergone radiation treatment in Asian countries, scarce reports on post-radiation sarcomas (PRSs) have been published. We investigated the feature and prognostic factors of PRSs in an Asian population. The Eastern Asian Musculoskeletal Oncology Group participated in this project. Cases obtained from 10 centers were retrospectively reviewed. Patients with genetic malignancy predisposition syndrome, or who had more than one type of malignancy before the development of secondary sarcoma were excluded. Forty-two high-grade sarcomas among a total of 43 PRSs were analyzed. There were 29 females and 13 males, with a median age of 58.5 years; 23 patients had bone tumors and 19 had soft tissue tumors. The most common primary lesion was breast cancer. The median latency period was 192 months. There were no differences in radiation dose, latency time, and survival rates between bone and soft tissue PRSs. The most common site and diagnosis were the pelvic area and osteosarcoma and malignant fibrous histiocytoma for bone and soft tissue PRSs. The median follow-up period was 25.5 months. Five-year metastasis-free and overall survival rates were 14.5% and 16.6%, and 39.1% and 49.6% for bone and soft tissue PRSs. Survival differences depending on initial metastasis and surgery were significant in soft tissue sarcomas. Although this study failed to find ethnic differences, it is the largest review on PRS in an Asian population. As early recognition through long-term surveillance is a key to optimal management, clinicians should take efforts to understand the real status of PRS.