title: Thyroid fine-needle aspiration biopsy and thyroid cancer diagnosis: a nationwide population-based study.
abstract: BACKGROUND
  Thyroid cancer is the most common endocrine gland malignancy and fine-needle aspiration biopsy is widely used for thyroid nodule evaluation. Repeated aspiration biopsies are needed due to plausible false-negative results. This study aimed to investigate the overall relationship between aspiration biopsy and thyroid cancer diagnosis, and to explore factors related to shorter diagnostic time.
  
  
  METHODS
  This nationwide retrospective cohort study retrieved data from the Longitudinal Health Insurance Database in Taiwan. Subjects without known thyroid malignancies and who received the first thyroid aspiration biopsy after 2004 were followed-up from 2004 to 2009 (n = 7700). Chi-square test, Kaplan-Meier survival analysis, and Cox proportional hazards model were used for data analysis.
  
  
  RESULTS
  Of 7700 newly-aspirated patients, 276 eventually developed thyroid cancer (malignancy rate 3.6%). Among the 276 patients with thyroid cancer, 61.6% underwent only one aspiration biopsy and 81.2% were found within the first year after the initial aspiration. Cox proportional hazards model revealed that aspiration frequency (HR 1.07, 95% CI 1.06-1.08), ultrasound frequency (HR 1.02, 95% CI 1.01-1.03), older age, male sex, and aspiration biopsies arranged by surgery, endocrinology or otolaryngology subspecialties were all associated with shorter time to thyroid cancer diagnosis.
  
  
  CONCLUSIONS
  About 17.4% of thyroid cancer cases received more than two aspiration biopsies and 18.8% were diagnosed one year after the first biopsy. Regular follow-up with repeated aspiration or ultrasound may be required for patients with clinically significant thyroid nodules.
authors.affiliation: Department of Community Medicine, Taipei City Hospital, Taipei, Taiwan; Institute of Public Health and Community Medicine Research Center, National Yang-Ming University, Taipei, Taiwan.
authors.forename: Li-Ying
authors.initials: LY
authors.lastname: Huang
authors.affiliation: Institute of Public Health and Community Medicine Research Center, National Yang-Ming University, Taipei, Taiwan; Department of Dentistry, Taipei City Hospital, Taipei, Taiwan; Department of Dentistry, School of Dentistry, National Yang-Ming University, Taipei, Taiwan.
authors.forename: Ya-Ling
authors.initials: YL
authors.lastname: Lee
authors.affiliation: Institute of Public Health and Community Medicine Research Center, National Yang-Ming University, Taipei, Taiwan.
authors.forename: Pesus
authors.initials: P
authors.lastname: Chou
authors.affiliation: Division of Endocrinology and Metabolism, Department of Internal Medicine, National Taiwan University Hospital and National Taiwan University College of Medicine, Taipei, Taiwan.
authors.forename: Wei-Yih
authors.initials: WY
authors.lastname: Chiu
authors.affiliation: Institute of Public Health and Community Medicine Research Center, National Yang-Ming University, Taipei, Taiwan; Department of Health Care Management, National Taipei University of Nursing and Health Sciences, Taipei, Taiwan; Department of Neurosurgery, Taipei City Hospital, Taipei, Taiwan.
authors.forename: Dachen
authors.initials: D
authors.lastname: Chu
mesh_terms: D000328:Adult; D044963:Biopsy, Fine-Needle; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D013624:Taiwan / Q000453:epidemiology; D013964:Thyroid Neoplasms / Q000401:mortality* / Q000473:pathology*