Single Center Results following Proton Beam Therapy in Children with Atypical Teratoid Rhabdoid Tumors of the Central Nervous System

Abstract

Purpose: Atypical teratoid rhabdoid tumor is a rare, embryonal, central nervous system tumor seen predominantly in infancy and childhood. Outcomes are generally dismal, with median survival estimated at 6 months to a year. The purpose of this study was to evaluate proton beam therapy (PBT) outcomes in this population. Materials and Methods: Sixteen patients with a diagnosis of atypical teratoid rhabdoid tumor were treated from November 2007 to January 2013 at the Indiana University Health Proton Therapy Center. All patients were treated with PBT. Fraction sizes of 1.8 Gy/fraction were used to deliver 28 to 33 fractions. Seven patients received craniospinal PBT. There were 12 male and 4 female patients. The median age at diagnosis was 18.5 months (range, 5 months to 39 years). Eight had metastatic disease at diagnosis. Fourteen patients underwent surgery. Fifteen patients received chemotherapy. Results: Median survival follow-up time was 3.18 years (or 38.2 months). The mean overall survival was estimated at 5.6 years (or 67.2 months; 95% confidence interval, 4.4–6.8 years). Patients of a median age of 18.5 months (range, 5.0–468 months) received a median radiation dose to the tumor bed of 54 Gy (range, 48.6–59.4 Gy). Eight patients also received craniospinal irradiation with a median dose of 36 Gy. Eleven patients showed no evidence of disease or stable disease, 3 patients were deceased, and 2 patients developed disease progression. Four patients suffered nausea and vomiting (common toxicity criteria [CTC] grade 2) as a result of treatment, and 4 patients also suffered moderate skin erythema (CTC grade 2). Two patients suffered from both weight loss and general fatigue during treatment. Conclusions: The PBT was well tolerated in this heavily treated population. In the background of poor survival, these early outcome data are promising. Additional follow- up is necessary