Second malignancies in patients with Ewing Sarcoma Family of Tumors: A population-based study

Abstract Background. Despite significant improvement in the outcome of patients with Ewing Sarcoma Family of Tumors (ESFT), second malignancies remain a problem that may compromise the outcome of some survivors. The Surveillance, Epidemiology and End-Results (SEER) database offers an opportunity to study second malignancies in a population-based cohort of patients. Methods. Cancer incidence rates were compared between the ESFT survivors and the general population using observed-to-expected ratios (O/E). Also, we studied the characteristics of patients with ESFT who developed second malignancies and compared them to those who did not. Results. We studied 1 166 patients with ESFT who were diagnosed from January 1973 to December 2005. Among them, 35 (3%) patients had records of second malignancy. Patients who received radiotherapy as part of their primary therapy had a higher chance of developing a second malignancy (odds ratio, 2.55; 95% CI, 1.09 to 6.00). Most solid tumors (78%) were diagnosed more than 5 years after diagnosis of ESFT while the majority (83%) of lymphatic/hematopoietic malignancies developed within five years of diagnosis. The 5-, 10-, and 20-year probability of developing a second malignancy were 2.1% ± 0.56%, 4.4% ± 0.95% and 8.0% ± 1.7%, respectively. The O/E ratio for developing a second malignancy was 4.10 (95%CI, 2.87 to 5.68) but was higher in children/adolescents (O/E, 9.94; 95%CI, 6.30 to 14.91). Conclusion. Having a second cancer following a diagnosis of ESFT is a known risk that may be increased by current therapies. This modest increase is justified by the benefit of these therapies in the majority of patients with ESFT.