Comparing Adult and Pediatric Rhabdomyosarcoma in the Surveillance, Epidemiology and End Results Program, 1973 to 2005: An Analysis of 2,600 Patients

PURPOSE: To compare clinical features and outcomes of adults and children reported to have rhabdomyosarcoma. PATIENTS AND METHODS: We analyzed data from 1,071 adults (age > 19 years) and 1,529 children (age < or = 19 years) reported in the public-access Surveillance, Epidemiology and End Results database as having rhabdomyosarcoma, diagnosed from 1973 to 2005. Survival estimates were determined using survival time with the end point being death from any cause. RESULTS: Adults with rhabdomyosarcoma had significantly worse outcome than children (5-year overall survival rates, 27% +/- 1.4% and 61% +/- 1.4%, respectively; P < .0001). Tumors in adults were more likely to be at an unfavorable site (65% v 55%; P < .0001) and to have histologies that are unusual during childhood, particularly the pleomorphic subtype (19%) and not otherwise specified (43%). Regional and distant spread was not more frequent in adults. Adults had significantly worse outcome than children with similar tumors. The most significant difference was in localized disease; 5-year survival estimates were 82% +/- 2.0% for children and 47% +/- 2.9% for adults (P < .0001). Multivariate analysis showed that age, histologic subtype, primary site location, stage, and local control with surgery and/or radiation were significant predictors of survival. However, alveolar subtype and unfavorable primary site lost significance when analysis was restricted to adults. CONCLUSION: Adults reported to have rhabdomyosarcoma had worse survival than children with similar tumors. Predictors of poor outcome in children were valid in adults except for alveolar histology and unfavorable tumor site.