Treatment of Nonmetastatic Rhabdomyosarcoma in Childhood and Adolescence: Third Study of the International Society of Paediatric Oncology—SIOP Malignant Mesenchymal Tumor 89

To improve outcome for children with nonmetastatic rhabdomyosarcoma and to reduce systematic use of local therapy. Five hundred three previously untreated patients aged from birth to 18 years, recruited between 1989 and 1995, were allocated to one of six treatment schedules by site and stage. Five-year overall survival (OS) and event-free survival (EFS) were 71% and 57%, respectively. Primary site, T-stage, and pathologic subtype were independent factors in predicting OS by multivariate analysis. Differences between EFS and OS reflected local treatment strategy and successful re-treatment for some patients after relapse. Patients with genitourinary nonbladder prostate tumors had the most favorable outcome (5-year OS, 94%): the majority were boys with paratesticular tumors treated successfully without alkylating agents. Patients with stage III disease treated with a novel six-drug combination showed improved survival compared with the Malignant Mesenchymal Tumor 84 study (MMT 84; 5-year OS, 60% v 42%, respectively). OS was not significantly better than that achieved in the previous MMT 84 study, but 49% of survivors were cured without significant local therapy. Selective avoidance of local therapy is justified in some patients, though further work is required to prospectively identify those for whom this is most applicable. Exclusion of alkylating agents is justified for the most favorable subset of patients. The value of the new six-drug chemotherapy combination is being evaluated further in a randomized study (MMT 95).