Background: Previous studies have shown that children who are treated for soft tissue sarcoma (STS) are at increased risk for developing second cancers. However, the risk for specific cancer sites and variations in risk by treatment and STS histology remain unclear.
Methods: The study evaluated 1499 children (age < 18 years) who survived for > or = 1 year after they were diagnosed with STS and who were reported to the Surveillance, Epidemiology, and End Results (SEER) population-based cancer registries from 1973 to 2000.
Results: Twenty-seven children developed 28 subsequent primary malignancies, compared with 4.5 expected malignancies based on general population rates (observed-to-expected [O/E] ratio = 6.3 (95% confidence interval [95% CI], 4.2-9.1). The risk of developing a subsequent malignancy was increased among children with rhabdomyosarcoma (observed = 11 malignancies; O/E ratio = 7.7), fibromatous neoplasms (observed = 9 malignancies; O/E ratio = 5.8), and other specified STS (observed = 7 malignancies; O/E ratio = 6.5). Initial therapy with radiation and chemotherapeutic agents was associated with a significantly higher risk of second malignancies compared with surgery alone (O/E ratio = 15.2 vs. 1.4; P < 0.0001). Elevated risks were observed for acute myeloid leukemia, cutaneous melanoma, female breast cancer, and sarcomas of the bone and soft tissue, with generally higher risks among patients who initially received combined modality therapy. Excess cancers of the oral cavity were prominent among long-term survivors. For several children, the pattern of multiple malignancies was consistent with a genetic syndrome, particularly neurofibromatosis type 1 and Li-Fraumeni syndrome.
Conclusions: The risk of second malignancies was increased for all histologic types of childhood STS and was particularly high among patients who received combined modality therapy.