Postoperative radiotherapy in the treatment of Ewing tumors: Influence of the interval between surgery and radiotherapy

Background: The impact of the timing of postoperative irradiation was evaluated in patients with Ewing tumors who received postoperative irradiation. Patients and Methods: 153 patients treated in the CESS 86 and EICESS 92 trials were evaluated in a retrospective analysis. They received surgery and postoperative irradiation as local treatment modalities. In 46 patients, postoperative irradiation was started within 60 days after surgery, in 107 patients after more than 60 days. A median dose of 45 Gy was administered. The median follow-up was 70 months. Results: There was no substanial difference between the two groups concerning risk factors for local failure and survival. The local control rate after 5 years was 98% in the group with early onset of radiation and 92% in the group with later onset (n.s.). There is no difference in event free survival between the two groups (both 64% after 5 years). If the cutpoint of the onset of postoperative irradiation was chosen after 90 days, there was no difference in local control or event free survival. Conclusions: Patients with early onset of postoperative irradiation show a trend for improved local control compared to patients with a later onset; the difference is statistically not significant. This trend has no influence on survival.