Re-irradiation for children with recurrent medulloblastoma in Toronto, Canada: a 20-year experience.

Purpose: Children with recurrent medulloblastoma have a poor prognosis. Re-irradiation is an option for some patients, but has not been well-studied in the era of molecular characterization for pediatric medulloblastoma. Methods: This was a retrospective cohort study of 14 children age 18 years and younger at initial diagnosis with recurrent medulloblastoma, who received two or more courses of radiation therapy (RT). Molecular subgrouping was performed using nanoString and was available for nine patients. The primary study endpoint was overall survival. Results: Re-irradiation (RT2) was directed at the supratentorial brain in six patients, infratentorial brain in one patient, and spine in seven patients. In addition, six patients received stem cell transplant as part of salvage therapy. Median OS for all patients was 12.4 months. One patient with recurrent Wnt-activated medulloblastoma remains alive with 154 months' survival; median survival was not reached for four patients with Group 4 disease, while three with Shh-activated disease had median survival of 2.2 months. A single patient with Group 3 disease died 4.3 months after RT2. Patients treated with RT2 to the spine for diffuse disease had poorer OS (p = 0.02), as compared to focal RT2 for intracranial recurrence. Distant failure, outside RT2 volumes, was the predominant pattern of recurrence after RT2. Conclusions: Re-irradiation for recurrent pediatric medulloblastoma can offer some patients disease control, particularly those with focally recurrent disease in the brain. Prospective studies are needed to confirm subgroups of patients who may benefit most from RT2. [ABSTRACT FROM AUTHOR]