Prognostic significance of tumor volume in localized Ewing's sarcoma of bone in children and adolescents.

A total of 60 consecutive patients with localized Ewing's sarcoma of bone who were entered into the Cooperative Ewing's Sarcoma Study of the German Society of Pediatric Oncology from January 1981 until April 1985 were evaluable for tumor volume at diagnosis. The tumor volume was calculated from plain X-rays and CT scans as ellipsoidal or cylindrical depending on the tumor configuration and presence or absence of a soft tissue component. The 3-year disease-free survival rate according to Kaplan-Meier life table analysis was 78% for tumors with a volume less than 100 ml compared to 17% for tumors greater than or equal to 100 ml volume. These results were independent of the site of the tumor, though larger tumors were primarily located in central and proximal extremity sites. Maximal tumor extension was less precise than tumor volume in predicting prognosis. The ratio of tumor volume to body surface area, body length, or body weight did not increase the ability to separate prognostic groups compared to tumor volume. The better prognosis for patients following radical surgery seems to be in part due to a biased distribution of tumor volumes within local therapy groups, since more patients with smaller tumors had surgery for local control.