The phase 3 AEWS1031 study found that in patients with nonmetastatic Ewing sarcoma treated with interval-compressed chemotherapy, the choice of local treatment—surgery, radiation, or both—did not independently affect the risk of the cancer returning in the same area. The overall 5-year local recurrence rate was low at 6%, reflecting major improvements in modern, multi-modality care.
Instead, recurrence risk was mainly driven by tumor-related factors. Larger tumors (volume ≥200 mL or size ≥8 cm), axial location (such as pelvis or spine), and older age were associated with higher recurrence rates. Smaller tumors and those in the extremities had lower risk.
Five-year recurrence rates were 5.0% for surgery alone, 8.4% for radiation alone, and 5.6% for combined treatment, with no statistically significant difference. This means doctors can choose surgery or radiation based on resectability, function, and patient preference, while focusing more aggressive strategies on high-risk patients with large or axial tumors.