COMPARING RHABDOMYOSARCOMA BETWEEN CHILDREN AND ADULTS

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

Iyad Sultan, Ibrahim Qaddoumi, Sameer Yaser, Carlos Rodriguez-Galindo, Andrea Ferrari

From the Departments of Pediatric Oncology and Medical Oncology, King Hussein Cancer Center, Amman, Jordan; Department of Pediatric Oncology, St Jude Children's Research Hospital, Memphis, TN; and the Pediatric Oncology Unit, Istituto Nazionale Tumori, Milan, Italy.

Corresponding author: Iyad Sultan, MD, King Hussein Cancer Center, Queen Rania Al Abdullah St, PO Box 1269, Amman 11941, Jordan; e-mail: isultan@khcc.jo.

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 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.