Clinical outcome of patients with Ewing sarcoma family of tumors of bone in Japan: The Japanese musculoskeletal oncology group cooperative study

BACKGROUND. Ewing sarcoma family of tumors (ESFT) of bone is extremely rare in Japan. The objectives of the current study were to assess the clinical outcome and prognostic factors of patients with ESFT of bone in Japan and to compare them between Euro-American and Japanese populations. METHODS. The authors conducted a retrospective analysis of 243 patients who were treated for ESFT of bone in Japan between 1981 and 2003. Local therapy was surgery in 35% of patients, surgery combined with radiotherapy in 40% of patients, radiotherapy alone in 22% of patients, and no local treatment in 3% of patients. All but 3 patients received various regimens of multidrug chemotherapy. RESULTS. The median patient age was 16 years. The primary disease sites were the trunk in 53% of patients and the extremities in 47% of patients. Forty-one patients had metastases at presentation. The median follow-up was 66 months. A univariate survival analysis demonstrated that patients who had metastases at presentation, primary site in the trunk, age ≥16 years, tumor size ≥10 cm, tumor that responded poorly to induction chemotherapy, and local treatment with radiotherapy alone had a significantly worse event-free survival (EFS). A multivariate analysis further verified that the former 3 factors were significant adverse prognostic factors. Of 201 patients with localized disease, 45 patients who received current chemotherapy regimens that included ifosfamide and etoposide had a significantly better 5-year EFS rate (67.6%) compared with other patients. CONCLUSIONS. The clinical outcome of patients with localized ESFT of bone in Japan has improved markedly with the use of current chemotherapy regimens that include ifosfamide and etoposide and has become comparable to the outcomes observed in other major series of Euro-American patients. The prognostic factors are also almost identical.