Head injury, diagnostic X-rays, and risk of medulloblastoma and primitive neuroectodermal tumor: a Children's Oncology Group study.

Objective: A comprehensive case-control study was conducted to determine potential risk factors for medulloblastoma/primitive neuroectodermal tumor (PNET), a common brain tumor in children. This analysis evaluated possible associations between previous head injury and ionizing radiation exposure through diagnostic X-rays and medulloblastoma/PNET.
Methods: Mothers of 318 cases <6 years of age at diagnosis between 1991 and 1997 and registered with the Children's Oncology Group were interviewed. Mothers of 318 matching controls were selected through random digit dialing and interviewed.
Results: An association was not detected between previous head injury (OR: 0.78, 95% CI: 0.40-1.5) or head X-ray for any reason including head injury with medulloblastoma/PNET. A statistically non-significant excess of cases reported having an X-ray for reason other than head injury (OR 2.3, 95% CI 0.91-5.7). When cases that received an X-ray for a common symptom of medulloblastoma/PNET were considered unexposed this association weakened (OR: 1.3, 95% CI: 0.49-3.7). No dose-response relationship was observed.
Conclusions: Head injury and exposure to diagnostic head X-rays were not associated with medulloblastoma/PNET in this study. Future studies should investigate all imaging procedures with ionizing radiation exposure including computed tomography scans and utilize radiation dose estimations.