Cancer in relatives of survivors of childhood sarcoma. Relatives of 88 long-term survivors of childhood sarcoma were examined for the familial cancer syndrome of sarcoma, breast cancer, and other neoplasms (Li-Fraumeni syndrome). Twenty-six of 402 close relatives developed cancer (expected, 23.8), including breast cancer in four mothers (expected, 3.1). Two sarcoma probands who developed second malignant tumors have multiple relatives with cancer and might have an inherited predisposition. An increased cancer risk and exceptional requirement for disease screening appear to be confined to first-degree relatives of a small fraction of children with sarcoma, notably probands with second cancers. 