title: Active and passive smoking in relation to lung cancer incidence in the Women's Health Initiative Observational Study prospective cohort.
abstract: BACKGROUND
  Lung cancer is the leading cause of worldwide cancer deaths. While smoking is its leading risk factor, few prospective cohort studies have reported on the association of lung cancer with both active and passive smoking. This study aimed to determine the relationship between lung cancer incidence with both active and passive smoking (childhood, adult at home, and at work).
  
  
  METHODS
  The Women's Health Initiative Observational Study (WHI-OS) was a prospective cohort study conducted at 40 US centers that enrolled postmenopausal women from 1993 to 1999. Among 93 676 multiethnic participants aged 50-79, 76 304 women with complete smoking and covariate data comprised the analytic cohort. Lung cancer incidence was calculated by Cox proportional hazards models, stratified by smoking status.
  
  
  RESULTS
  Over 10.5 mean follow-up years, 901 lung cancer cases were identified. Compared with never smokers (NS), lung cancer incidence was much higher in current [hazard ratio (HR) 13.44, 95% confidence interval (CI) 10.80-16.75] and former smokers (FS; HR 4.20, 95% CI 3.48-5.08) in a dose-dependent manner. Current and FS had significantly increased risk for all lung cancer subtypes, particularly small-cell and squamous cell carcinoma. Among NS, any passive smoking exposure did not significantly increase lung cancer risk (HR 0.88, 95% CI 0.52-1.49). However, risk tended to be increased in NS with adult home passive smoking exposure ≥30 years, compared with NS with no adult home exposure (HR 1.61, 95% CI 1.00-2.58).
  
  
  CONCLUSIONS
  In this prospective cohort of postmenopausal women, active smoking significantly increased risk of all lung cancer subtypes; current smokers had significantly increased risk compared with FS. Among NS, prolonged passive adult home exposure tended to increase lung cancer risk. These data support continued need for smoking prevention and cessation interventions, passive smoking research, and further study of lung cancer risk factors in addition to smoking. CLINICALTRIALS.GOV: NCT00000611.
authors.affiliation: Department of Medicine, Division of Oncology, Stanford University School of Medicine, Stanford.
authors.forename: A
authors.initials: A
authors.lastname: Wang
authors.affiliation: Quantitative Sciences Unit, Stanford University School of Medicine, Palo Alto.
authors.forename: J
authors.initials: J
authors.lastname: Kubo
authors.affiliation: Department of Epidemiology and Biostatistics, Indiana University, Bloomington.
authors.forename: J
authors.initials: J
authors.lastname: Luo
authors.affiliation: Quantitative Sciences Unit, Stanford University School of Medicine, Palo Alto.
authors.forename: M
authors.initials: M
authors.lastname: Desai
authors.affiliation: Quantitative Sciences Unit, Stanford University School of Medicine, Palo Alto.
authors.forename: H
authors.initials: H
authors.lastname: Hedlin
authors.affiliation: Department of Medicine, Division of Oncology, Stanford University School of Medicine, Stanford.
authors.forename: M
authors.initials: M
authors.lastname: Henderson
authors.affiliation: Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance.
authors.forename: R
authors.initials: R
authors.lastname: Chlebowski
authors.affiliation: Center for Research on HealthCare, University of Pittsburgh, Pittsburgh.
authors.forename: H
authors.initials: H
authors.lastname: Tindle
authors.affiliation: Program in Epidemiology, Division of Public Health Sciences, Fred Hutchinson Cancer Research Center, Seattle.
authors.forename: C
authors.initials: C
authors.lastname: Chen
authors.affiliation: Division of Epidemiology, Stanford University School of Medicine, Stanford.
authors.forename: S
authors.initials: S
authors.lastname: Gomez
authors.affiliation: Department of Epidemiology, Brigham and Women's Hospital, Harvard Medical School, Boston.
authors.forename: J E
authors.initials: JE
authors.lastname: Manson
authors.affiliation: Karmanos Cancer Institute, Wayne State University, Detroit.
authors.forename: A G
authors.initials: AG
authors.lastname: Schwartz
authors.affiliation: Department of Social and Preventive Medicine, University at Buffalo, Buffalo.
authors.forename: J
authors.initials: J
authors.lastname: Wactawski-Wende
authors.affiliation: Karmanos Cancer Institute, Wayne State University, Detroit.
authors.forename: M
authors.initials: M
authors.lastname: Cote
authors.affiliation: Department of Medicine, Division of Oncology, Stanford University School of Medicine, Stanford.
authors.forename: M I
authors.initials: MI
authors.lastname: Patel
authors.affiliation: Department of Medicine, Stanford Prevention Research Center, Stanford University School of Medicine, Stanford, USA.
authors.forename: M L
authors.initials: ML
authors.lastname: Stefanick
authors.affiliation: Department of Medicine, Division of Oncology, Stanford University School of Medicine, Stanford. Electronic address: hwakelee@stanford.edu.
authors.forename: H A
authors.initials: HA
authors.lastname: Wakelee
mesh_terms: D000368:Aged; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008175:Lung Neoplasms / Q000453:epidemiology*; D008875:Middle Aged; D017698:Postmenopause; D016016:Proportional Hazards Models; D011446:Prospective Studies; D012306:Risk; D012307:Risk Factors; D012907:Smoking / Q000009:adverse effects*; D011795:Surveys and Questionnaires; D014028:Tobacco Smoke Pollution / Q000009:adverse effects*; D016387:Women's Health
chemical_list: D014028:Tobacco Smoke Pollution
keywords: lung cancer; lung cancer histology; never smokers; passive smokers; smoking