title: Age of diagnosing physician impacts the incidence of thyroid cancer in a population.
abstract: BACKGROUND
  Thyroid ultrasound and fine-needle aspiration (FNA) have been implicated in the overdiagnosis of thyroid cancer. To study how the use of diagnostic tools impacts thyroid cancer incidence, we propose using physician age as a surrogate. We aimed to determine whether thyroid cancer incidence is higher in areas with a high density of young physicians compared with areas with a high density of older physicians.
  
  
  METHODS
  SEER 13 database was used to determine thyroid cancer incidence. These data were linked to the Area Resource File data (2000), containing information on physician age at a county-specific level. Cohorts were divided by age based on the concentration of physicians within a population of 1,000,000 persons. The study period was divided into two time periods (1992-1995, 2006-2009).
  
  
  RESULTS
  The incidence of thyroid cancer was stable in areas with high concentrations of young and older physicians during the 1992-1995 time period [<35: 5.97; 55-64: 6.82; ≥65: 6.70 (per 100,000py)]. Areas with high concentrations of young physicians had an increased incidence of thyroid cancer compared with areas of high concentrations of older physicians during the 2006-2009 period [<35: 13.3; 55-64: 9.86; ≥65: 7.47 (per 100,000py)].
  
  
  CONCLUSIONS
  Thyroid cancer incidence was lower in areas with high concentrations of older physicians. This may be the result of increased adoption of thyroid ultrasound and FNA among younger physicians who have trained after diagnostic tools became common. Age of the diagnosing physician is a surrogate for diagnostic utility contributing to thyroid cancer trends.
authors.affiliation: Endocrine Surgery Research Program, Department of Surgery, University of Chicago, Pritzker School of Medicine, 5841 S. Maryland Avenue, MC 4052, Chicago, IL, 60637, USA, Snagar29@gmail.com.
authors.forename: Sapna
authors.initials: S
authors.lastname: Nagar
authors.forename: Briseis
authors.initials: B
authors.lastname: Aschebrook-Kilfoy
authors.forename: Edwin L
authors.initials: EL
authors.lastname: Kaplan
authors.forename: Peter
authors.initials: P
authors.lastname: Angelos
authors.forename: Raymon H
authors.initials: RH
authors.lastname: Grogan
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D044963:Biopsy, Fine-Needle; D002983:Clinical Competence; D005260:Female; D005387:Finland / Q000453:epidemiology; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D010820:Physicians; D010818:Practice Patterns, Physicians' / Q000706:statistics & numerical data*; D012042:Registries; D018426:SEER Program; D013964:Thyroid Neoplasms / Q000175:diagnosis / Q000453:epidemiology*