Timing of radiation in children with medulloblastoma/PNET.

Background: To evaluate the importance of timing of radiation therapy in children with PNET/medulloblastoma, treated at the Brazilian National Cancer Institute (INCA).

Procedure: The records of 101 children with confirmed diagnosis of medulloblastoma were retrospectively reviewed. Patients had a median follow-up of 48 months (0.5-241 months). The age varied from 0.8 to 17.5 years (median: 7.6 years) and 21.7% were 3 years old or younger.

Results: According to the data collected from patients that received treatment for medulloblastoma from 1983 to 2001, the overall survival (OS) rate was 53% and the Disease Free Survival (DFS) rate was 40%. Multivariate analysis showed that under age 3 years, presence of neoplasic cells in the cerebrospinal fluid (CSF) at presentation or subtotal tumor resection resulted in a worse OS. The patients that received a biological effective dose (BED) greater than 44 Gy10 had better prognosis. Two-thirds of the patients had complete response after the initial treatment. Among them, 50% (34 patients) recurred, and of those 34 patients, 42% of them (14 patients) had recurrence in the posterior fossa.

Conclusion: Surgery with total resection of the tumor and absence of neoplasic cells in the CSF are effective predictors of better OS. Radiotherapy was more effective when a BED was greater than 44 Gy10.