Evaluation of outcome and prognostic factors in extraosseous Ewing sarcoma.
Data on extraosseous Ewing sarcoma (EES) with uniform chemotherapy protocol are minimal. We aimed to examine this aspect in our patients, identify prognostic factors and compare the same with osseous Ewing sarcoma. A single institutional data review of patients with EES treated between June 2003 and November 2011 with uniform chemotherapy and evaluated on intent-to-treat analysis was done. Of 374 patients with Ewing sarcoma, 60 (16%) were EES with median age 16 years; 20 (33%) had metastases. After median follow-up of 25 months (range: 1.7-104.4), 5-year event free survival (EFS), OS, and local-control-rate were 47.1 ± 7.9%, 61.6 ± 7.8%, and 77.9 ± 8.6%, respectively for entire EES cohort. In multivariate analysis, hemoglobin ≤ 10 g/dl (P = 0.03), and white blood cell count (WBC) >11 × 10(9) /L (P = 0.009) predicted inferior EFS for the entire EES cohort. Low hemoglobin (P = 0.05) and high LDH (P = 0.01) predicted inferior OS for the entire EES cohort on multivariate analysis. As compared to the cohort of skeletal primary (n = 314), higher proportion of patients underwent surgery in the cohort of EES (P = .003); EFS (P = 0.004) and OS (P = 0.08) were superior for patients with EES than patients with skeletal Ewing sarcoma. These data of EES suggests that low hemoglobin and high WBC count adversely affect EFS. Overall outcome was significantly better for EES than skeletal primary tumors.