Survival of very young children with medulloblastoma (primitive neuroectodermal tumor of the posterior fossa) treated with craniospinal irradiation

Purpose: Very young children with medulloblastoma are considered to have a worse prognosis than older children. As radiotherapy remains an important p art of the treatment, the adverse prognosis could be due to inadequate radi ation treatment rather than biological factors. We analyzed the published l iterature to examine the impact of radiotherapy on survival in this group. Methods and Materials: A Medline search was performed and we reviewed studi es of treatment of medulloblastoma where radiotherapy was delivered using m egavoltage equipment and the minimum follow-up allowed the calculation of 5 -year survival rates. Results: Thirty-nine studies were published between 1979 and 1996 with a tr eatment including craniospinal irradiation and boost to the posterior fossa . Eleven studies comprising 1366 patients analyzed survival by age at diagn osis. Eight of 11 studies showed a worse 5-year survival for the younger pa tient group which reached statistical significance in two. There is also a suggestion of a higher proportion of children with metastatic disease at pr esentation in the very young age group. The usual policy in younger childre n was to give a lower dose of radiotherapy to the craniospinal axis (CSA) a nd posterior fossa (PE) with reduction of dose in the range of 15 to 25% co mpared to standard treatment. As dose reduction to the posterior fossa is a ssociated with worse survival and local recurrence is the predominant site of failure, the major determinant of worse survival in very young children with medulloblastoma may be suboptimal radiotherapy. Protocols including po stoperative chemotherapy with delayed, omitted, or only local tumor irradia tion do not reach survival rates of protocols with standard radiotherapy, a lso suggesting a continued importance for irradiation. Conclusion: Very young children with medulloblastoma have a worse prognosis than older children. Inadequate radiation dose and technique to the primar y tumor region may be a major contributing factor. Current chemotherapeutic regimes alone are not sufficient to compensate for reduced radiation doses and volumes. (C) 1998 Elsevier Science Inc.