Comparison of proton beam therapy and radiotherapy for pediatric solid tumors based on meta-analyses

Abstract

Proton beam therapy (PBT) was introduced for pediatric solid tumors because its physical dose distribution can reduce normal tissue irradiation. However, whether tumor control and survival outcomes are maintained compared with those of photon radiotherapy remain unclear. According to a lecture at the 67th Annual Meeting of the Japanese Society of Pediatric Hematology/Oncology, this article summarizes the disease-specific meta-analyses conducted as part of the Tsukuba Review Project. The reviewed diseases included rhabdomyosarcoma, neuroblastoma, Ewing’s sarcoma, medulloblastoma, intracranial ependymoma, and central nervous system germ cell tumors. Currently available evidence does not consistently suggest inferior survival or local control after PBT compared to photon radiotherapy. However, these findings should not be interpreted as proof of superiority or strict non-inferiority, because the analyses were based mainly on aggregate data from observational studies. Patient selection, treatment era, irradiation field, systemic therapy, and surgery remain important confounding factors. The principal value of PBT in pediatric oncology is to maintain tumor control while reducing normal tissue dose and mitigating late toxicities. Prospective registries with long-term follow-up are required.