Outcomes and prognostic factors of major salivary gland tumors treated with proton beam radiation therapy

Background Proton beam radiation therapy (PBRT) has dosimetric advantages compared to photon radiation therapy for the treatment of major salivary gland tumors (MSGTs). Methods Patients with non-metastatic MSGTs treated at a single proton therapy center from October 2013 to October 2018 were retrospectively reviewed. Results Sixty-eight patients with MSGTs were included and the most common site and histology were the parotid gland (75.0%) and adenoid cystic carcinoma (22.1%), respectively. The 3-year rates of locoregional control, progression-free survival, and overall survival were 95.1% (95% CI: 89.9%-100.0%), 80.7% (70.2%-92.7%), and 96.1% (95% CI: 90.9%-100.0%), respectively. Conclusion In a large cohort of MSGTs treated with PBRT, the rates of locoregional control were high in short-term follow-up and treatment was well tolerated.