This study reported outcomes of 194 patients diagnosed with IDH-mutated WHO grade 2 (n = 128) and WHO grade 3 (n = 66) glioma treated with proton radiation. With a median follow-up 5.1 years, 5-year OS was 85% for WHO grade 2 patients and 67% WHO grade 3. AEs of 80% grade 1, 7% grade 2, 13% grade 3, and 0% grade 3+ were observed. The authors concluded that these results demonstrated the effectiveness of PRT for IDH-mutated glioma WHO grade 2 and 3.