3152 - Clinical Characteristics and Incidence of Radiation-Induced Sarcoma in Cancer Patients

Purpose/Objective(s): Radiation therapy is a critical component of cancer treatment, with over 50% of patients requiring radiotherapy. However, it carries a potential risk of secondary malignancies, particularly sarcoma. This study aims to analyze the incidence and clinical characteristics of radiation-induced sarcoma in cancer patients.

Materials/Methods: A retrospective analysis was conducted on 6,743 cancer patients treated between August 2010 and June 2023. Patients with multiple primary tumors were screened, and cases with secondary primary bone and soft tissue sarcomas were identified. Radiation history was confirmed through medical records and follow-ups. Diagnostic criteria for radiation-induced sarcoma included: (1) sarcoma occurring within or adjacent to the previous radiation field; (2) a minimum interval of 6 months between radiotherapy and sarcoma diagnosis; and (3) histological confirmation of sarcoma with a different origin from the primary tumor. Statistical analysis was performed using standard software.

Results: Among 493 patients with multiple primary tumors, 24 had secondary primary bone and soft tissue sarcomas, with 16 meeting the criteria for radiation-induced sarcoma. Radiation-induced sarcoma accounted for 0.36% of all cancer patients and 3.25% of multiple primary tumor cases. The primary tumors associated with radiation-induced sarcoma included breast cancer (4 cases), rectal cancer (3 cases), cervical cancer (3 cases), nasopharyngeal cancer (3 cases), esophageal cancer (1 case), seminoma (1 case), and ventricular astrocytoma (1 case). Pathologically, soft tissue sarcoma predominated (11 cases), followed by osteosarcoma (5 cases). The median age at diagnosis of the first primary tumor was 39 years, while the median age at diagnosis of radiation-induced sarcoma was 53 years. The average interval between radiotherapy and sarcoma development was 117 months. Gene expression analysis in 3 cases revealed significantly reduced WNT10A expression compared to the first primary sarcoma.

Conclusion: Radiation-induced sarcoma is rare and primarily associated with favorable-prognosis primary tumors such as breast, cervical, rectal, and nasopharyngeal cancers, often diagnosed at a younger age. For patients with secondary primary bone and soft tissue sarcomas, a detailed radiation history should be obtained to determine potential associations.