Radiation Treatment for Ewing Sarcoma Family of Tumors in Adult Patients: A Single Institution's Experience Over 40 Years.

Purpose/Objectives: To report prognostic factors and long-term outcomes in adults with Ewing sarcoma treated with definitive radiotherapy. Materials and Methods: We reviewed patients 18 years old and above with nonmetastatic Ewing sarcoma treated with radiotherapy +/- chemotherapy or surgery. Outcomes were stratified by age (30 and above vs. younger than 30 y), soft tissue extension, tumor size (>= 8.5 vs. <8.5 cm), tumor location, resection (yes vs. no), and treatment era (1970-1992 vs. 1993-2012). Toxicities were scored using the RTOG criteria. Results: Fifty-five patients (21 women) were treated with radiotherapy. Average age at diagnosis: 26.7 years (38 patients below 30 vs. 17 patients 30 y and above). A total of 43 had soft tissue extension (78%). Median tumor size: 8.5 cm. Most tumors were in the pelvis (40%), followed by the lower (27%) and upper (24%) extremities. All but 1 patient received chemotherapy; 13 underwent resection. Median dose: 55 Gy. Median follow-up: 3.6 years; 17.5 years for living patients. The 5-year overall (OS) and cause-specific survival (CSS) rates were both 46%. OS and CSS rates were unaffected by age (P=0.97), tumor size (P=0.12), or tumor location (P=0.99). Soft tissue extension portended a significantly poorer prognosis for 5-year OS and CSS: 37% vs. 82% (with and without, respectively; P = 0.04). Patients who underwent resection had improved 5-year OS and CSS: 77% vs. 37%, respectively (P=0.01). Patients treated after 1993 had improved 5-year OS: 58% vs. 37% (P=0.0264). Conclusions: Adult patients with Ewing sarcoma experience similar treatment outcomes regardless of age at diagnosis. Soft tissue extension represents a poor prognostic factor. Aggressive trimodality therapy achieved the highest OS and CSS.