RTRB-08: HELICAL TOMOTHERAPY-BASED CRANIOSPINAL IRRADIATION: MATURE OUTCOMES OF A PROSPECTIVE FEASIBILITY STUDY

PURPOSE: To report mature outcomes in a cohort of patients treated on a prospective feasibility study of helical tomotherapy-based craniospinal irradiation (CSI). METHODS: After written informed consent, patients needing neuraxial irradiation were accrued and treated on an Institutional Review Board-approved study. Following CSI, patients received boost irradiation based upon histology and extent of disease. Concurrent chemotherapy was not given during CSI; however patients with high-risk disease received sequential adjuvant systemic chemotherapy. Patients were followed up longitudinally for survival and toxicity. RESULTS: Twenty patients (median age of 15 years) constituted the study cohort. Tomotherapy-based CSI was well tolerated with self-limiting and reversible acute toxicity. Four (20%) patients needed growth factor or platelet support during CSI. Significant late neuro-toxicity was seen in only 1 (5%) patient. None of the patients developed symptomatic radiation pneumonitis or second new malignancy. At a median follow-up of 62 months (inter-quartile range 24-71 months), the 5-year progression-free survival and overall survival (with respective standard error) for the entire cohort was 50% (+11.2%) and 55% (+11.1%) respectively. Outcomes within the cohort varied significantly; patients with favorable biology disease had good outcomes while patients with high-risk, metastatic, or recurrent disease fared poorly reflecting inherently aggressive biology. CONCLUSIONS: Helical tomotherapy is an ideal platform for planning, verification and delivery of supine CSI in clinical practice resulting in moderate, self-limiting, reversible acute toxicity and modest delayed toxicity. Patterns of failure and survival outcomes are largely dependent upon disease biology and are not any different compared to conventional techniques.