Incidence and outcomes of extremity soft-tissue sarcomas in children

Background: We studied the outcomes of pediatric extremity tumors on a population scale. Methods: The Surveillance, Epidemiology, and End Results database (1973-2006) was queried for all patients under 20 y of age. Results: Overall, 1175 patients were identified. The median age at diagnosis was 12 y, but most patients were ≥10 y of age (72%, n = 842). Most tumors were non-rhabdomyosarcoma soft tissue sarcomas (NRSTS) (79%, n = 879). The most common tissue of origin was muscle (43%, n = 474). Most rhabdomyosarcoma (RMS) (n = 220) were alveolar type (n = 140). Most patients presented with local disease (64%, n = 699), and underwent surgical intervention (88%, n = 1027), but did not have radiotherapy (62%, n = 710). RMS was more likely to present in younger children (P < 0.001) and with distant disease (P < 0.001). Older patients were more likely to receive radiotherapy than infants (P < 0.001). Overall 5-y survival was 79%. RMS had significantly worse 5-y survival (56% versus 85% for NRSTS, P < 0.001). Surgical intervention was associated with higher 5-y survival (84% versus 48%, P < 0.001). Radiotherapy was associated with worse 5-y survival (74% versus 83%, P = 0.002). Multivariate analysis identified RMS (HR 2.20, P < 0.001), nerve and muscle (not synovial sarcoma) tissue of origin (HR 2.26, P = 0.002, and HR 1.59, P = 0.036), regional or distant disease (HR 1.65, P = 0.011, and HR 5.96, P < 0.001, respectively), and lack of surgical intervention (HR 2.20, P < 0.001) as independent predictors of poor outcome. Conclusions: Extremity sarcomas are most common in older children. RMS is more common in younger children, but is associated with lower survival, and is an independent prognostic indicator of mortality.