2ND MALIGNANCIES AFTER EWINGS-SARCOMA - RADIATION DOSE-DEPENDENCY OF SECONDARY SARCOMAS

Background: An excess risk of second malignancies has been reported in survivors of Ewing's sarcoma. We examined a multiinstitutional data b ase to reevaluate the risk among survivors of Ewing's sarcoma and to i dentify possible causal factors. Methods: Information was derived from a data base that included 266 survivors of Ewing's sarcoma. Cumulativ e incidence rates of second malignancies were calculated. Contribution s of clinical features, type and dose of chemotherapy, and cumulative radiation dose to the risk of second malignancies were evaluated. Resu lts: After a median follow-up duration of 9.5 years (range, 3.0 to 30) , 16 patients have developed second malignancies, which included 10 sa rcomas (five osteosarcomas, three fibrosarcomas, and two malignant fib rous histiocytomas) and six other malignancies (acute myeloblastic leu kemia, acute lymphoblastic leukemia, meningioma, bronchioalveolar carc inoma, basal cell carcinoma, and carcinoma-in-situ of the cervix), The median latency to the diagnosis of the second malignancy was 7.6 year s (range, 3.5 to 25.7). The estimated cumulative incidence rates at 20 years for any second malignancy and for secondary sarcoma were 9.2% ( SD = 2.7%) and 6.5% (SD = 2.4%), respectively. The cumulative incidenc e rate of secondary sarcoma was radiation dose-dependent (P = .002). N o secondary sarcomas developed among patients who had received less th an 48 Gy, while the absolute risk of secondary sarcoma was 130 cases p er 10,000 person-years of observation among patients who had received greater than or equal to 60 Gy. Conclusion: The overall risk of second malignancies after Ewing's sarcomas is similar to that associated wit h treatment for other childhood cancers. The radiation dose-dependency of secondary sarcomas justifies modification in therapy to reduce rad iation doses. (C) 1996 by American Society of Clinical Oncology.