Medulloblastoma and Ependymoma Tumors
Brain tumors are the most common solid tumors affecting children and adolescents. Medulloblastoma and ependymoma tumors are two common pediatric brain tumors that require radiation therapy for cure. Both tumors occur in young children, the median age being 5 years or less. All medulloblastomas and ~60% of ependymomas arise in the posterior fossa. Medulloblastoma is a tumor that commonly metastasizes through the cerebrospinal fluid and necessitates craniospinal irradiation (CSI) in children 3 years and older, even when disease is localized. Typical radiation doses for medulloblastoma are 18-36 Gy CSI followed by a boost to the tumor bed to 54 Gy. Treatment for localized ependymoma requires 50.4-59.4 Gy radiation to the tumor bed only. While radiation is an essential part of curative treatment for these tumors, radiation to the developing brain can also result in adverse late effects.
There are two major types of external beam radiation: photon (or X-ray) based radiation and particle (proton) radiation. Photon radiation is the most widely available and is the modality with which many cancer patients are treated. Proton radiation, however, has recently garnered attention for its physical characteristics that allows the radiation dose to be localized to the tumor target while better sparing the healthy nearby tissues. In contrast to photons, there is no exit dose to tissues beyond the tumor.
Our Research Study
Proton radiation is less widely available and is also very expensive. Long-term health outcomes research is required to determine if the properties of proton radiation translate to an improvement in health among survivors of childhood brain tumors. Our study involves a comparison of neurocognitive and health-related quality of life outcomes among patients treated with proton radiation at Massachusetts General Hospital (MGH) and patients treated with photon radiation at Emory University/Children’s Healthcare of Atlanta (CHOA).