Proton radiotherapy is equally effective and causes fewer long-term side effects compared with standard photon (x-ray) radiation therapy (RT) for the treatment of pediatric patients with the most common type of malignant brain tumor.
Although often recognized as an effective method of delivering more targeted treatment for patients with cancer, proton radiotherapy is still not widely available in most countries. Likewise, little research has been conducted on the efficacy of proton therapy in pediatric patients with medulloblastoma, a common type of pediatric brain tumor, for whom targeted therapy could avoid irradiating critical areas such as the brain, eyes, and ears.
In a phase 2 clinical trial, investigators assessed whether treatment with proton radiotherapy could produce similar outcomes with fewer adverse side effects compared with conventional methods, particularly photon RT. A total of 45 evaluable patients with medulloblastoma were enrolled and treated with proton radiotherapy in the trial. All patients were evaluated for hearing loss, cognitive decline, and neuroendocrine toxic effect at 3 and 5 years.
Significant hearing loss due to treatment was found in 12% of patients after 3 years and 16% after 5 years, similar to what has been reported in those treated with photon RT. However, no cardiac, gastrointestinal, or pulmonary effects were reported using proton therapy, all of which have been found after use of photon radiotherapy.
In addition, there was no significant impact on cognitive function, and most negative effects (verbal comprehension and processing speed) were observed in patients who were under the age of 8 years when treated. Progression-free survival was 80% and 83% at Year 3 and Year 5, respectively; comparable to what has been found in studies of photon RT.
Therefore, researchers concluded that treatment with proton radiotherapy had similar survival outcomes and acceptable toxicity compared with conventional methods of treatment and may therefore be an alternative to less targeted photon-based treatments.
