title: A pooled analysis of case-control studies of thyroid cancer: cigarette smoking and consumption of alcohol, coffee, and tea.
abstract: OBJECTIVE
  To analyze the role of smoking, alcohol, coffee and tea in relation to thyroid cancer, we conducted a pooled analysis of 14 case-control studies conducted in the United States, Europe, and Asia.
  
  
  METHODS
  The sample consisted of 2725 thyroid cancer cases (2247 females, 478 males) and 4776 controls (3699 females, 1077 males). Conditional logistic regression with stratification on study, age at diagnosis, and gender was used to compute odds ratios and 95% confidence intervals.
  
  
  RESULTS
  Thyroid cancer risk was reduced in persons who had ever smoked. The relationship was more pronounced in current smokers (OR = 0.6, 95% CI = 0.6-0.7) than former smokers (OR = 0.9, 95% CI = 0.8-1.1). There were significant trends of reduced risk with greater duration and frequency of smoking. For consumption of wine and beer, there was a significant trend of decreasing thyroid cancer risk (p = 0.02) that was not maintained after adjustment for current smoking (p = 0.12). Thyroid cancer risk was not associated with consumption of coffee or tea. These findings were consistent in both gender-specific and histology-specific (papillary and follicular) analyses.
  
  
  CONCLUSIONS
  Pooled analyses of these geographically diverse case-control data indicate a reduced thyroid cancer risk associated with current smoking. A reduced risk associated with alcohol was eliminated after adjustment for smoking, and caffeinated beverages did not alter thyroid cancer risk.
authors.affiliation: Department of Preventive Medicine, Keck School of Medicine, University of Southern California, Los Angeles, CA 90089, USA.
authors.forename: Wendy J
authors.initials: WJ
authors.lastname: Mack
authors.forename: Susan
authors.initials: S
authors.lastname: Preston-Martin
authors.forename: Luigino
authors.initials: L
authors.lastname: Dal Maso
authors.forename: Rosaria
authors.initials: R
authors.lastname: Galanti
authors.forename: Min
authors.initials: M
authors.lastname: Xiang
authors.forename: Silvia
authors.initials: S
authors.lastname: Franceschi
authors.forename: Arne
authors.initials: A
authors.lastname: Hallquist
authors.forename: Fan
authors.initials: F
authors.lastname: Jin
authors.forename: Laurence
authors.initials: L
authors.lastname: Kolonel
authors.forename: Carlo
authors.initials: C
authors.lastname: La Vecchia
authors.forename: Fabio
authors.initials: F
authors.lastname: Levi
authors.forename: Athena
authors.initials: A
authors.lastname: Linos
authors.forename: Eiliv
authors.initials: E
authors.lastname: Lund
authors.forename: Anne
authors.initials: A
authors.lastname: McTiernan
authors.forename: Kiyohiko
authors.initials: K
authors.lastname: Mabuchi
authors.forename: Eva
authors.initials: E
authors.lastname: Negri
authors.forename: Gun
authors.initials: G
authors.lastname: Wingren
authors.forename: Elaine
authors.initials: E
authors.lastname: Ron
mesh_terms: D000428:Alcohol Drinking; D016022:Case-Control Studies; D003069:Coffee; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D012907:Smoking; D013662:Tea; D013964:Thyroid Neoplasms / Q000209:etiology*
chemical_list: D003069:Coffee; D013662:Tea