Analyzing the Usage of Pencil-Beam Proton Radiotherapy for Patients With Atypical Teratoid Rhabdoid Tumor of Central Nervous System

Abstract

Atypical teratoid rhabdoid tumor of the central nervous system is a rare tumor affecting very young children. Treatment of ATRT includes different regimens of radiotherapy depending on age, stage and treatment protocols. Proton therapy allows to reduce acute and late toxicity. This reduction (among other benefits) helps to finish irradiation without interruptions. It matters for kids receiving craniospinal irradiation as well as for kids receiving radiotherapy after high dose chemotherapy.We reviewed data of 30 patients with ATRT treated with pencil-beam proton therapy from 06.2018 to 12.2020. We analyzed treatment characteristics, outcomes and other factors that could be prognostic for progression free survival.Median age at the start of radiotherapy was 28 months. Patients received local radiotherapy (18 patients) and craniospinal irradiation (12 patients). Total dose in case of local radiotherapy was 54 Gy. A median craniospinal dose was 29.8 Gy (24-36 Gy). Four patients got re-irradiation course because of local or leptomeningeal progression. One of them received craniospinal re-irradiation. All the patients who were 5 years old and younger received daily general anesthesia (sedation) during radiotherapy course. Two of the patients did not finish course of radiotherapy because of distant progression. Median follow-up was 10 months. No interruptions were needed for any of the patients. Inability to achieve gross tumor resection (P = 0.01) and M3-stage (P = 0.03) were the most unfavorable prognostic factors for progression-free survival.This is one of the largest reports of using pencil-beam proton therapy for children with ATRT of CNS treated in one facility. Proton therapy was well tolerated even by patients receiving re-irradiation course. Further research should be conducted in order to get information about late toxicity and survival outcomes.