title: Association between development of hypothyroidism and improved survival in patients with head and neck cancer.
abstract: OBJECTIVE
  To determine if the development of hypothyroidism has an effect on the outcome of advanced-stage head and neck squamous cell carcinoma.
  
  
  METHODS
  Retrospective database analysis.
  
  
  METHODS
  Tertiary care center.
  
  
  METHODS
  The study population comprised 155 patients with advanced-stage head and neck squamous cell carcinoma.
  
  
  METHODS
  Patients underwent radiation therapy alone or in combination with chemotherapy and surgery when indicated.
  
  
  METHODS
  Kaplan-Meier analysis was used to assess survival, not adjusting for timing of the detection of hypothyroidism. The following 2 analyses were then performed to adjust for the timing of detection: (1) hypothyroidism was assessed as a time-varying covariate in a Cox proportional hazards model and (2) a landmark analysis was conducted at 9, 12, 15, 18, 21, and 24 months using the Kaplan-Meier method.
  
  
  RESULTS
  Of the 155 patients, 59 developed hypothyroidism, defined as a thyrotropin level greater than 5.5 mIU/L (institutional value). An unadjusted Kaplan-Meier analysis indicated that patients who develop hypothyroidism have significantly better survival than patients who do not (P<.001, log-rank test). After adjusting for the timing of hypothyroidism, a Cox proportional hazards analysis indicated that survival was better, but not statistically significant, for patients who developed hypothyroidism (hazard ratio, 0.62; P=.12); results from a landmark analysis supported this finding (P values ranged from .11 to .19).
  
  
  CONCLUSIONS
  Development of hypothyroidism may be associated with improved survival and increased recurrence-free survival. Larger, prospective studies appear warranted to test the beneficial effect of hypothyroidism.
authors.affiliation: Head and Neck Institute, and Department of Radiation Oncology, Cleveland Clinic Foundation, Cleveland, Ohio 44195, USA.
authors.forename: Marc
authors.initials: M
authors.lastname: Nelson
authors.forename: Aleck
authors.initials: A
authors.lastname: Hercbergs
authors.forename: Lisa
authors.initials: L
authors.lastname: Rybicki
authors.forename: Marshall
authors.initials: M
authors.lastname: Strome
mesh_terms: D005260:Female; D006801:Humans; D007037:Hypothyroidism / Q000150:complications*; D008297:Male; D008875:Middle Aged; D010039:Otorhinolaryngologic Neoplasms / Q000150:complications / Q000401:mortality* / Q000473:pathology / Q000628:therapy; D016016:Proportional Hazards Models; D012008:Recurrence; D015996:Survival Rate