title: External beam radiotherapy for differentiated thyroid cancer.
abstract: OBJECTIVE
  To evaluate the efficacy of external beam radiation therapy (EBRT) for differentiated thyroid carcinomas.
  
  
  METHODS
  Forty-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.
  
  
  RESULTS
  The 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.
  
  
  CONCLUSIONS
  EBRT increases the likelihood of local-regional control for patients with locally advanced differentiated thyroid carcinoma.
authors.affiliation: Department of Radiation Oncology, University of Florida College of Medicine, Gainesville, FL, USA.
authors.forename: Kenyon M
authors.initials: KM
authors.lastname: Meadows
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Amdur
authors.forename: Christopher G
authors.initials: CG
authors.lastname: Morris
authors.forename: Douglas B
authors.initials: DB
authors.lastname: Villaret
authors.forename: Ernest L
authors.initials: EL
authors.lastname: Mazzaferri
authors.forename: William M
authors.initials: WM
authors.lastname: Mendenhall
mesh_terms: D000328:Adult; D000368:Aged; D001707:Biopsy, Needle; D001918:Brachytherapy; D018265:Carcinoma, Papillary, Follicular / Q000401:mortality / Q000473:pathology* / Q000532:radiotherapy* / Q000601:surgery; D015331:Cohort Studies; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D009361:Neoplasm Invasiveness / Q000473:pathology; D009367:Neoplasm Staging; D011379:Prognosis; D018714:Radiotherapy, Adjuvant; D012189:Retrospective Studies; D018570:Risk Assessment; D015996:Survival Rate; D013964:Thyroid Neoplasms / Q000401:mortality / Q000473:pathology* / Q000532:radiotherapy* / Q000601:surgery; D013965:Thyroidectomy / Q000379:methods; D016896:Treatment Outcome