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

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.

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.

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).

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.