Age, Stage, and Radiotherapy, But Not Primary Tumor Site, Affects the Outcome of Patients With Malignant Rhabdoid Tumors

Background. Malignant rhabdoid tumors (MRTs) are aggressive and often fatal; the Surveillance, Epidemiology, and End Results (SEER) database offers an opportunity to study this rare malignancy. Methods. From the SEER database, we extracted records of patients with a reported diagnosis of MRT and analyzed them for clinical features and survival rates by univariate and multivariate analyses. Results. For the 229 patients included in our data, who were diagnosed from 1986 to 2005, primary tumors were located in the central nervous system (CNS) (35%), kidneys (20%), and extra-renal non-cranial sites (ERNC-MRTs) (45%). Most patients with renal and CNS tumors were less than 18 years old (87%) and 96%, respectively) while more than half of the patients with ERNC-MRTs (61%) were adults. Among staged tumors, 23% were localized, 34% regional, and 43% distant. Renal tumors had significantly more metastatic disease (47%; P=0.006) than ERNC-MRTs. The estimated 5-year survival for the entire group was 33 +/- 3.4% (SE). Univariate and multivariate analyses showed that age at diagnosis (2-18 years), localized stage of tumors, and use of radiotherapy were significantly associated with improved survival. Adults had a better outcome than young children (<2 years old) but a poorer outcome than older children (2-18 years old); tumor stage, but not radiotherapy use, affected outcome in adults. The survival and prognostic factors of children diagnosed before and after 2000 did not differ significantly. Conclusion. Our population-based study indicates that age at diagnosis, tumor stage, and use of radiotherapy favorably impact survival rates of patients with MRTs. Pediatr Blood Cancer 2010;54: 35-40. (C) 2009 Wiley-Liss, Inc.