title: A prospective cohort study of body size and risk of head and neck cancers in the NIH-AARP diet and health study.
abstract: BACKGROUND
  The association between body size and head and neck cancers (HNCA) is unclear, partly because of the biases in case-control studies.
  
  
  METHODS
  In the prospective NIH-AARP cohort study, 218,854 participants (132,288 men and 86,566 women), aged 50 to 71 years, were cancer free at baseline (1995 and 1996), and had valid anthropometric data. Cox proportional hazards regression was used to examine the associations between body size and HNCA, adjusted for current and past smoking habits, alcohol intake, education, race, and fruit and vegetable consumption, and reported as HR and 95% confidence intervals (CI).
  
  
  RESULTS
  Until December 31, 2006, 779 incident HNCAs occurred: 342 in the oral cavity, 120 in the oro- and hypopharynx, 265 in the larynx, 12 in the nasopharynx, and 40 at overlapping sites. There was an inverse association between HNCA and body mass index, which was almost exclusively among current smokers (HR = 0.76 per each 5 U increase; 95% CI, 0.63-0.93), and diminished as initial years of follow-up were excluded. We observed a direct association with waist-to-hip ratio (HR = 1.16 per 0.1 U increase; 95% CI, 1.03-1.31), particularly for cancers of the oral cavity (HR, 1.40; 95% CI, 1.17-1.67). Height was also directly associated with total HNCAs (P = 0.02), and oro- and hypopharyngeal cancers (P < 0.01).
  
  
  CONCLUSIONS
  The risk of HNCAs was associated inversely with leanness among current smokers, and directly with abdominal obesity and height.
  
  
  CONCLUSIONS
  Our study provides evidence that the association between leanness and risk of HNCAs may be due to effect modification by smoking.
authors.affiliation: Division of Cancer Epidemiology and Genetics, National Cancer Institute, Bethesda, Maryland. Digestive Oncology Research Center, Digestive Disease Research Institute, Tehran University of Medical Sciences, Tehran, Iran. arash.etemadi@nih.gov.
authors.forename: Arash
authors.initials: A
authors.lastname: Etemadi
authors.affiliation: UKCRC Centre of Excellence for Public Health, Queen's University, Belfast, United Kingdom.
authors.forename: Mark G
authors.initials: MG
authors.lastname: O'Doherty
authors.affiliation: Division of Cancer Epidemiology and Genetics, National Cancer Institute, Bethesda, Maryland.
authors.forename: Neal D
authors.initials: ND
authors.lastname: Freedman
authors.affiliation: AARP, Washington, District of Columbia.
authors.forename: Albert R
authors.initials: AR
authors.lastname: Hollenbeck
authors.affiliation: Division of Cancer Epidemiology and Genetics, National Cancer Institute, Bethesda, Maryland.
authors.forename: Sanford M
authors.initials: SM
authors.lastname: Dawsey
authors.affiliation: Division of Cancer Epidemiology and Genetics, National Cancer Institute, Bethesda, Maryland.
authors.forename: Christian C
authors.initials: CC
authors.lastname: Abnet
mesh_terms: D000368:Aged; D015992:Body Mass Index; D002294:Carcinoma, Squamous Cell / Q000209:etiology*; D015331:Cohort Studies; D004032:Diet; D006258:Head and Neck Neoplasms / Q000209:etiology*; D006801:Humans; D008875:Middle Aged; D011446:Prospective Studies; D012307:Risk Factors; D000077195:Squamous Cell Carcinoma of Head and Neck