European intergroup studies (MMT4-89 and MMT4-91) on childhood metastatic rhabdomyosarcoma: final results and analysis of prognostic factors.

Final results are presented from two consecutive European studies for patients with metastatic rhabdomyosarcoma (RMS) to identify prognostic variables and determine the value of high-dose chemotherapy (HDCT) in complete remission. A total of 174 patients aged 3 months to 18 years participated. From 1989 to 1991, patients received four cycles of intensive multiagent chemotherapy. From 1991 to 1995, patients achieving complete remission received consolidation with HDCT. All received local therapy (surgery, radiation therapy) according to response. At a median follow-up of 8 years, 5-year overall survival (OS) and event-free survival (EFS) for the whole group were 24% and 20%, respectively. No statistical difference was found between HDCT and standard chemotherapy (5-year OS, 36% v 27%; EFS 29% v 23%). Univariate analysis identified primary tumor in parameningeal, extremity, or other sites; age younger than 1 year and older than 10 years; bone or bone marrow metastases; multiple metastases; and multiple sites of metastases as unfavorable prognostic factors for OS and EFS. Multivariate analysis identified unfavorable site, bone or bone marrow involvement, and unfavorable age as independently unfavorable factors. Two subgroups were identified. Those with fewer than two unfavorable factors had 5-year EFS and OS of 40% and 47%, respectively. Patients with > or = two unfavorable factors had 5-year EFS and OS of 7.5% and 9%, respectively. A minority of patients with metastatic RMS have better survival than overall results for this population suggest. Those in the highest risk group have such poor survival that they are candidates for first-line novel therapies. There is no evidence that consolidation with HDCT improves outcome.