Standard-risk medulloblastoma: Hyperfractionated radiotherapy

Abstract

The standard treatment for medulloblastomas includes a craniospinal radiotherapy that causes devastating late effects on growth, neurocognitive development, and endocrinologic function, especially in childhood and young adults. Decreasing the dose to the craniospinal axis has a positive impact on late toxicity. However the risk of relapses increase. As the repair half-life of normal tissue is much shorter than that of tumor tissues, non accelerated hyperfractionated craniospinal radiotherapy (HFRT) can theoretically reduce delayed effects of radiation injury on healthy tissues while effectively destroying tumor cells. Two series of standard risk medulloblastomas HRFT received twice daily dose of 1 Gy separated by 4–6 h up to 36 Gy to the craniospinal axis. One delivered 72 Gy to the tumor bed followed by chemotherapy ; the other a boost to the operative cavity of 68 Gy twice daily dose of 1 Gy without chemotherapy. Both gave encouraging results in term of both survival and lack of toxicity. The use of HFRT thus deserves further evaluation in randomised protocols, such as the recently closed SIOP PNET IV.