Recurrence in childhood medulloblastoma.

Thirty-eight consecutive children treated according to the HIT2000 and HIT91 studies for medulloblastoma who suffered 40 recurrence events were identified from a neuroradiological database. Relapse was associated with younger median age compared with all children treated on HIT2000. Eight patients relapsed with isolated local recurrence. There was no correlation with incomplete surgical removal or violation of the respective treatment protocol. Four patients were younger than 4 years at time of initial presentation and thus were not treated primarily with radiotherapy, suggesting that delayed radiotherapy might be a contributing factor. Meningeal dissemination was present in 32 events; 16 were located in the frontal region, 8 of which were isolated nodular frontal and frontobasal meningeal disease. Circumscribed meningeal recurrences were associated with better overall survival (OS) compared with diffuse, widespread recurrences. Isolated frontobasal meningeal relapses are a well-known phenomenon in medulloblastomas even years after treatment and have been correlated to an underdose of radiation in many literature reports. However, in our patients there was no correlation to possible treatment violations, indicating that inadequate radiation dose to the frontobasal region was unlikely to be a causative factor. Surgical technique varied due to the multicentric nature of our study, so position during surgery was not recognized as a predisposing factor for frontobasal recurrence.