title: Alcohol Intake and Risk of Thyroid Cancer: A Meta-Analysis of Observational Studies.
abstract: OBJECTIVE
  The purpose of this study was to assess whether alcohol intake is associated with the risk of thyroid cancer by a meta-analysis of observational studies.
  
  
  METHODS
  We searched PubMed and EMBASE in June of 2015 to locate eligible studies. We included observational studies such as cross-sectional studies, case-control studies, and cohort studies reporting odd ratios (ORs) or relative risk (RRs) with 95% confidence intervals (CIs).
  
  
  RESULTS
  We included 33 observational studies with two cross-sectional studies, 20 case-controls studies, and 11 cohort studies, which involved a total of 7,725 thyroid cancer patients and 3,113,679 participants without thyroid cancer in the final analysis. In the fixed-effect model meta-analysis of all 33 studies, we found that alcohol intake was consistently associated with a decreased risk of thyroid cancer (OR or RR, 0.74; 95% CI, 0.67 to 0.83; I2=38.6%). In the subgroup meta-analysis by type of study, alcohol intake also decreased the risk of thyroid cancer in both case-control studies (OR, 0.77; 95% CI, 0.65 to 0.92; I2=29.5%; n=20) and cohort studies (RR, 0.70; 95% CI, 0.60 to 0.82; I2=0%; n=11). Moreover, subgroup meta-analyses by type of thyroid cancer, gender, amount of alcohol consumed, and methodological quality of study showed that alcohol intake was significantly associated with a decreased risk of thyroid cancer.
  
  
  CONCLUSIONS
  The current meta-analysis of observational studies found that, unlike most of other types of cancer, alcohol intake decreased the risk of thyroid cancer.
authors.affiliation: Division of Food Science and Culinary Arts, Food and Nutrition Major, Shinhan University, Uijeongbu, Korea.
authors.forename: Seung-Hee
authors.initials: SH
authors.lastname: Hong
authors.affiliation: Department of Cancer Control and Policy, Graduate School of Cancer Science and Policy, National Cancer Center, Goyang, Korea.|Molecular Epidemiology Branch, Division of Cancer Epidemiology and Prevention, Research Institute, National Cancer Center, Goyang, Korea.|Department of Family Medicine, Center for Cancer Prevention and Detection, Hospital, National Cancer Center, Goyang, Korea.
authors.forename: Seung-Kwon
authors.initials: SK
authors.lastname: Myung
authors.affiliation: School of Nursing, Shinhan University, Uijeongbu, Korea.
authors.forename: Hyeon Suk
authors.initials: HS
authors.lastname: Kim
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000428:Alcohol Drinking / Q000009:adverse effects*; D016022:Case-Control Studies; D002648:Child; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D064887:Observational Studies as Topic; D016017:Odds Ratio; D012306:Risk; D013964:Thyroid Neoplasms / Q000453:epidemiology* / Q000209:etiology*; D055815:Young Adult
keywords: Alcohol drinking; Case-control studies; Cohort studies; Meta-analysis; Thyroid neoplasms