External beam radiotherapy for differentiated thyroid cancer

PurposeTo evaluate the efficacy of external beam radiation therapy (EBRT) for differentiated thyroid carcinomas.MethodsForty-two patients with a locally advanced or recurrent differentiated thyroid carcinoma received high-dose EBRT. Thirty-three patients had local-regional disease and 9 patients also had asymptomatic disease metastases. Twenty patients (48%) had macroscopic local-regional disease before EBRT.ResultsThe 5-year outcomes for the overall population and for the subset of those without distant metastases before EBRT were local-regional control (88% and 89%, respectively), cause-specific survival (80% and 86%, respectively), and overall survival (54% and 60%, respectively). Local-regional control was improved for patients with microscopic residual disease compared with macroscopic disease, those with previously untreated tumors, and for those who received more than 64 Gy.ConclusionEBRT increases the likelihood of local-regional control for patients with locally advanced differentiated thyroid carcinoma.