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.
(Copyright 2009 Wiley-Liss, Inc.)