Long‐term outcomes of evolving treatment regimens in Ewing sarcoma survivors diagnosed 1970–1999: A report from the Childhood Cancer Survivor Study

BACKGROUND: Survivors of Ewing sarcoma (EWS) are at significant long-term risk of treatment- and disease-related complications. The purpose of this study was to characterize long-term outcomes in EWS survivors according to treatment regimen. METHODS: Five-year survivors of EWS diagnosed between 1970 and 1999 from the Childhood Cancer Survivor Study were included. Late mortality (>5 years from diagnosis), subsequent malignant neoplasms (SMNs), and severe to fatal chronic health conditions (CHCs) by chemotherapy regimen were compared. Patients were compared to siblings via cumulative incidence and proportional hazards models. Standardized mortality ratios (SMRs) compared late mortality between survivors and the general population. RESULTS: Survivors (N = 739) had higher all-cause (SMR, 6.16; 95% CI, 5.36-7.05), SMN-related (SMR, 9.24; 95% CI, 6.92-12.08), cardiac-related (SMR, 4.53; 95% CI, 2.81-6.93), and noncardiopulmonary health-related (SMR, 2.04; 95% CI, 1.25-3.15) mortality compared with the general population. Compared with siblings (N = 5040), survivors had an increased risk of developing CHCs (any: hazard ratio [HR], 5.49; 95% CI, 4.58-6.59; cardiovascular: HR, 4.59; 95% CI, 3.67-5.74; neurological: HR, 2.82; 95% CI, 1.72-4.63; respiratory: HR, 5.37; 95% CI, 2.76-10.5; renal: HR, 4.61; 95% CI, 2.26-9.40). Between chemotherapy groups within EWS, there were no statistically significant differences in all-cause, SMN-caused, or health-related late mortality and the risk of developing SMNs or CHCs (any, cardiovascular, neurological, or respiratory), except that the vincristine, doxorubicin, and cyclophosphamide (VDC) plus ifosfamide and etoposide (IE) group had a higher risk of renal complications (HR, 2.55; 95% CI, 1.07-11.7; 30-year incidence was 0.56% for VDC and 3.2% for VDC/IE). CONCLUSIONS: No differences in late mortality, SMNs, and most CHCs were observed between patients who received VDC versus VDC/IE. Aging EWS survivors' elevated risk of morbidity and mortality underscores the need for lifelong survivorship care and therapies that reduce the risk for late effects.