Subsequent cancer in patients with Ewing's sarcoma.

Among 31 long-term survivors of Ewing's sarcoma, two patients developed second primary cancers, compared to an expected number of 0.03 (relative risk = 72; 95% confidence limit = 8-259). One patient had renal medullary neuroblastoma, which is not known to be related to Ewing's tumor or its therapy. The second patient had a bone fibrosarcoma, arising at the primary tumor site, which was thought to be radiation-induced. The risk of radiation-induced bone sarcomas was lower, although not significantly so, than in a recently reported series of Ewing's tumor. These two reports suggest that patients with Ewing's sarcoma have a tendency to develop radiogenic sarcomas following primary megavoltage radiation therapy. The lowest radiation dose consistent with local tumor eradication should be employed to minimize the risk of subsequent radiogenic cancer.