This retrospective study evaluated 22 patients with thyroid cancer treated with PBT to a total dose of 60 GyRBE adjuvantly and 70 GyRBE for gross disease. With a median follow-up 26 months, 1-year local regional recurrence (LRR) was 0%, and overall survival (OS) was 90% for all patients. Acute grade 3+ toxicities occurred in 27% of patients, the most frequent being dermatitis (27%). Three patients required a percutaneous endoscopic gastrostomy tube after radiation therapy (RT), 2 owing to progression. There were no grade 4+ toxicities. The authors concluded that PBT for thyroid cancer was feasible and effective with minimal toxicities.