title: Optimal detection of hypothyroidism in early stage laryngeal cancer treated with radiotherapy.
abstract: BACKGROUND
  Hypothyroidism following radiation therapy (RT) for treatment of Head and Neck Cancer (HNC) is a common occurrence. Rates of hypothyroidism following RT for Early Stage Laryngeal Squamous Cell Carcinoma (ES-LSCC) are among the highest. Although routine screening for hypothyroidism is recommended; its optimal schedule has not yet been established. We aim to determine the prevalence and optimal timing of testing for hypothyroidism in ES-LSCC treated with RT.
  
  
  METHODS
  We conducted a population-based cohort study. Data was extracted from a prospective provincial head and neck cancer database. Demographic, survival data, and pre- and post-treatment thyroid stimulating hormone (TSH) levels were obtained for patients diagnosed with ES-LSCC from 2008-2012. Inclusion criteria consisted of patients diagnosed clinically with ES-LSCC (T1 or 2, N0, M0) treated with curative intent. Patients were excluded if there was a history of hypothyroidism before the treatment or any previous history of head and neck cancers.
  
  
  RESULTS
  Ninety-five patients were included in this study. Mean age was 66.1 years (range: 44.0-88.0 years) and 82.3% of patients were male. Glottis was the most common subsite at 77.9% and the average follow-up was 40 months (Range: 12-56 months). Five-year overall survival generated using the Kaplan-Meier method was 79%. Incidence of hypothyroidism after RT was found to be 46.9%. The greatest frequency of developing hypothyroidism was at 12 months.
  
  
  CONCLUSIONS
  We found a high prevalence of hypothyroidism for ES-LSCC treated with RT, with the highest rate at 12 months. Consequently, we recommend possible routine screening for hypothyroidism using TSH level starting at 12 months. To our knowledge, this is the first study to suggest the optimal timing for the detection of hypothyroidism.
authors.affiliation: Division of Otolaryngology-Head and Neck Surgery, University of Alberta Hospital, 1E4.29 WMC, 8440 - 112 Street, Edmonton, AB, T6G 2B7, Canada.
authors.forename: Graeme B
authors.initials: GB
authors.lastname: Mulholland
authors.affiliation: Division of Otolaryngology-Head and Neck Surgery, University of Alberta Hospital, 1E4.29 WMC, 8440 - 112 Street, Edmonton, AB, T6G 2B7, Canada.
authors.forename: Han
authors.initials: H
authors.lastname: Zhang
authors.affiliation: Division of Radiation Oncology, McMaster University, Hamilton, Canada.
authors.forename: Nhu-Tram A
authors.initials: NT
authors.lastname: Nguyen
authors.affiliation: Northern Ontario School of Medicine, Sudbury, Canada.
authors.forename: Nicholas
authors.initials: N
authors.lastname: Tkacyzk
authors.affiliation: Division of Otolaryngology-Head and Neck Surgery, University of Alberta Hospital, 1E4.29 WMC, 8440 - 112 Street, Edmonton, AB, T6G 2B7, Canada.
authors.forename: Hadi
authors.initials: H
authors.lastname: Seikaly
authors.affiliation: Division of Otolaryngology-Head and Neck Surgery, University of Alberta Hospital, 1E4.29 WMC, 8440 - 112 Street, Edmonton, AB, T6G 2B7, Canada.
authors.forename: Daniel
authors.initials: D
authors.lastname: O'Connell
authors.affiliation: Division of Otolaryngology-Head and Neck Surgery, University of Alberta Hospital, 1E4.29 WMC, 8440 - 112 Street, Edmonton, AB, T6G 2B7, Canada.
authors.forename: Vincent L
authors.initials: VL
authors.lastname: Biron
authors.affiliation: Division of Otolaryngology-Head and Neck Surgery, University of Alberta Hospital, 1E4.29 WMC, 8440 - 112 Street, Edmonton, AB, T6G 2B7, Canada. Jeffrey.Harris@albertahealthservices.ca.
authors.forename: Jeffrey R
authors.initials: JR
authors.lastname: Harris
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000416:Alberta / Q000453:epidemiology; D015415:Biomarkers / Q000097:blood; D001706:Biopsy; D002294:Carcinoma, Squamous Cell / Q000150:complications / Q000175:diagnosis / Q000532:radiotherapy*; D018572:Disease-Free Survival; D004307:Dose-Response Relationship, Radiation; D042241:Early Diagnosis; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007037:Hypothyroidism / Q000175:diagnosis* / Q000453:epidemiology / Q000209:etiology; D015994:Incidence; D007822:Laryngeal Neoplasms / Q000150:complications / Q000175:diagnosis* / Q000532:radiotherapy; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging / Q000379:methods*; D011379:Prognosis; D011446:Prospective Studies; D020266:Radiotherapy, Conformal / Q000379:methods*; D015996:Survival Rate / Q000639:trends; D013972:Thyrotropin / Q000097:blood; D013997:Time Factors
chemical_list: D015415:Biomarkers; D013972:Thyrotropin