Age Is an Independent Prognostic Factor in Rhabdomyosarcoma: A Report from the Soft Tissue Sarcoma Committee of the Children's Oncology Group

Background. Although age <1 year at diagnosis has been associated with a worse prognosis in rhabdomyosarcoma (RMS), the relationship of age at diagnosis to clinical presentation and outcome has not been evaluated carefully. We reviewed data from recent Intergroup Rhabdomyosarcoma Study Committee (later called Group, IRSG) trials to examine this relationship in order to estimate prognosis more accurately and further refine treatment. Procedure. We used data from IRS-III, -IV Pilot, and -IV (1983-97, N = 2,343) to study the relationship of patient age with clinical features and prognosis in a large cohort of patients treated with contemporary therapy. Results. We showed that, after adjusting for important prognostic factors, age was an independent risk factor for treatment failure and patients could be classified into three failure-risk categories based on age (i.e., <1 year; 1-9 years; >10 years). Infants and adolescents were more likely to have unfavorable features, including alveolar or undifferentiated tumors and advanced Group and Stage, and also had significantly poorer failure-free survival (FFS) than did children aged 1-9 (53 and 51% vs. 72%, P < 0.001). Although there was a difference in FFS among age categories, there was no evidence that age influences outcome within the three categories. Conclusions. Since age relates independently to outcome after adjustment for known risk factors, it is likely that other factors, including perhaps patients' tolerance of protocol-specified therapy, explain this relationship.