title: History of periodontal disease diagnosis and lung cancer incidence in the Women's Health Initiative Observational Study.
abstract: OBJECTIVE
  While some evidence suggests that periodontal disease (PD) might be positively associated with lung cancer, prospective studies in women are limited. Previous findings may reflect residual confounding by smoking. The study aims to determine whether history of PD diagnosis is associated with incident lung cancer in a large cohort of postmenopausal women.
  
  
  METHODS
  Prospective analyses were conducted in a cohort of 77,485 postmenopausal women enrolled in the Women's Health Initiative Observational Study. History of PD (prevalence of 26.1 %) was self-reported, and 754 incident lung cancer cases occurred during an average 6.8 (SD ± 2.6) years of follow-up. Cox proportional hazards regression analysis was used to estimate hazard ratios (HRs) and 95 % confidence intervals (CIs).
  
  
  RESULTS
  Overall, PD was positively associated with lung cancer risk after adjusting for detailed smoking history including smoking status and pack-years of smoking (HR 1.24, 95 % CI 1.07-1.45). There was a positive additive interaction between PD with pack-years of smoking (p = 0.02), suggesting a potential synergistic effect between PD and smoking intensity on lung cancer. The association between PD and lung cancer was stronger in former smokers. When restricted to never-smokers, PD was not associated with lung cancer (HR 1.02, 95 % CI 0.68-1.53).
  
  
  CONCLUSIONS
  Periodontal disease was not independently associated with lung cancer in non-smoking postmenopausal women. However, smoking and PD jointly increased lung cancer risk beyond that expected from the sum of the each effect separately. The potential synergism between PD and smoking on lung cancer warrants further examination.
authors.affiliation: Department of Epidemiology and Environmental Health, School of Public Health and Health Professions, University at Buffalo, The State University of New York, 270 Farber Hall, Buffalo, NY, 14214, USA, xiaodanm@buffalo.edu.
authors.forename: Xiaodan
authors.initials: X
authors.lastname: Mai
authors.forename: Michael J
authors.initials: MJ
authors.lastname: LaMonte
authors.forename: Kathleen M
authors.initials: KM
authors.lastname: Hovey
authors.forename: Ngozi
authors.initials: N
authors.lastname: Nwizu
authors.forename: Jo L
authors.initials: JL
authors.lastname: Freudenheim
authors.forename: Mine
authors.initials: M
authors.lastname: Tezal
authors.forename: Frank
authors.initials: F
authors.lastname: Scannapieco
authors.forename: Andrew
authors.initials: A
authors.lastname: Hyland
authors.forename: Christopher A
authors.initials: CA
authors.lastname: Andrews
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Genco
authors.forename: Jean
authors.initials: J
authors.lastname: Wactawski-Wende
mesh_terms: D000368:Aged; D015331:Cohort Studies; D005260:Female; D006801:Humans; D015994:Incidence; D008175:Lung Neoplasms / Q000453:epidemiology*; D008875:Middle Aged; D010510:Periodontal Diseases / Q000453:epidemiology*; D017698:Postmenopause; D012907:Smoking / Q000453:epidemiology; D014481:United States / Q000453:epidemiology; D016387:Women's Health