Systematic Review and Meta-Analysis of Proton Beam Therapy Versus Photon Radiotherapy for Medulloblastoma:...

Background/Objectives: PBT enables precise targeting of tumors, which reduces side effects on surrounding organs, with particularly significant benefits for pediatric tumors. However, the efficacy of PBT compared to photon RT for pediatric medulloblastoma is unclear. A meta-analysis to assess the efficacy of PBT vs. photon RT for this disease was performed. Methods: Articles focusing on postoperative primary medulloblastoma from 1990 to 2022 were systematically reviewed and survival outcomes were extracted for medulloblastoma treated with PBT or photon RT. Meta-regression was used to identify predictive factors for treatment outcomes, including modality (PBT vs. photon RT), disease risk classification, gender, and age. Results: From 935 records, 18 articles were included (14 on photon RT, with 6 focusing on high-risk cases, and 4 on PBT). In standard-risk cases, the 1-, 3-, and 5-year overall survival (OS) rates were 95.5% (95% CI: 87.2-98.4%) vs. 96.7% (95% CI: 93.5-98.4%) (p = 0.1210); 89.8% (95% CI: 85.3-92.9%) vs. 88.0% (95% CI: 83.7-91.3%) (p = 0.5416); and 82.9% (95% CI: 76.6-87.6%) vs. 82.4% (95% CI: 77.2-86.5%) (p = 0.8313), respectively. For high-risk cases, the OS rates were 88.9% (95% CI: 85.5-91.6%); 73.6% (95% CI: 60.9-82.8%); and 68.6% (95% CI: 56.1-78.3%), respectively. The 1-, 3-, and 5-year progression-free survival (PFS) rates in standard-risk cases were 95.2% (95% CI: 91.8-97.2%) vs. 93.8% (95% CI: 89.4-96.5%) (p = 0.5275); 82.9% (95% CI: 77.3-87.2%) vs. 82.5% (95% CI: 80.1-84.7%) (p = 0.4294); and 79.6% (95% CI: 73.1-84.6%) vs. 77.0% (95% CI: 72.7-80.8%) (p = 0.3938), respectively. For high-risk cases, the PFS rates were 83.5% (95% CI: 77.0-88.3%); 64.8% (95% CI: 53.2-74.2%); and 60.4% (95% CI: 47.0-71.4%), respectively. Meta-regression analysis indicated no significant differences in 1- to 5-year OS and PFS between radiation modalities. Standard-risk cases were significantly associated with better OS and PFS. Younger age was significantly associated with 1- and 2-year OS and 1-year PFS, and male gender was significantly associated with 3-year OS and 3-year PFS. Conclusions: Postoperative irradiation for pediatric medulloblastoma using PBT has a therapeutic effect comparable to that of photon RT. This suggests that PBT is a useful option among RT modalities for medulloblastoma.