A study from Japan reported outcomes of 62 patients with sinonasal tumors treated with protons to 60 GyRBE in 15 fractions or 60.8 GyRBE in 16 fractions for mucosal melanoma and 70.2 GyRBE in 26 fractions for other histologic subtypes. The 2-year LC, progression-free survival, and OS rates of all patients were 92%, 50%, and 76%, respectively.

Sixteen grade ≥3 late toxicities were observed in 12 patients (19%), including 11 events resulting in visual impairment; the most common was cataract. There was 1 grade 4 toxicity, and there were no grade 5 toxicities. The authors concluded that SSPT was well tolerated and yielded good LC for sinonasal malignant tumors and considered SSPT to be a leading treatment modality.