title: CT screening for lung cancer: Importance of emphysema for never smokers and smokers.
abstract: OBJECTIVE
  To address the prevalence of lung cancer in high and low-risk people according to their smoking history, age, and CT findings of emphysema.
  
  
  METHODS
  We reviewed the baseline low-dose CT scans of 62,124 current, former and never smokers, aged 40-90 to determine the prevalence of lung cancer. We performed logistic regression analysis of the prevalence of lung cancer to determine the odds ratio (OR) for emphysema, conditionally on age, female gender, and ethnicity.
  
  
  RESULTS
  The prevalence of lung cancer was 1.4% (95% CI: 1.3-1.6) for current smokers, 1.1% (95% CI: 1.0-1.2) for former smokers, and 0.4% (95% CI: 0.3-0.6) for never smokers. Emphysema was identified in 28.5% (6,684), 20.6% (5,422), and 1.6% (194) of current, former, and never smokers, respectively. The prevalence of lung cancer among current smokers was 1.1% for those without emphysema vs. 2.3% for those with emphysema (odds ratio [OR] 1.8; 95% confidence interval [CI]: 1.4-2.2) and the corresponding difference for former smokers was 0.9% vs. 1.8% (OR: 1.7; 95% CI: 1.3-2.2), and for never smokers, it was 0.4% vs. 2.6% (OR: 6.3; 95% CI: 2.4-16.9).
  
  
  CONCLUSIONS
  Identification of emphysema in low-dose CT scans increases the risk of lung cancer and is important in determining follow-up of current, former, and never smokers.
authors.affiliation: Department of Radiology, Mount Sinai School of Medicine, New York, NY, United States. Electronic address: Claudia.Henschke@mountsinai.org.
authors.forename: Claudia I
authors.initials: CI
authors.lastname: Henschke
authors.affiliation: Department of Radiology, Mount Sinai School of Medicine, New York, NY, United States; Institute of Translational Epidemiology, Mount Sinai School of Medicine, New York, NY, United States.
authors.forename: Rowena
authors.initials: R
authors.lastname: Yip
authors.affiliation: Institute of Translational Epidemiology, Mount Sinai School of Medicine, New York, NY, United States.
authors.forename: Paolo
authors.initials: P
authors.lastname: Boffetta
authors.affiliation: City University of New York at Queens College, Flushing, NY, United States.
authors.forename: Steven
authors.initials: S
authors.lastname: Markowitz
authors.affiliation: City University of New York at Queens College, Flushing, NY, United States.
authors.forename: Albert
authors.initials: A
authors.lastname: Miller
authors.affiliation: Azumi General Hospital, Nagano, Japan.
authors.forename: Takaomi
authors.initials: T
authors.lastname: Hanaoka
authors.affiliation: Cancer Hospital, Chinese Academy of Medical Science, Beijing, China.
authors.forename: Ning
authors.initials: N
authors.lastname: Wu
authors.affiliation: Clinica Universitaria de Navarra, Pamplona, Spain.
authors.forename: Javier J
authors.initials: JJ
authors.lastname: Zulueta
authors.affiliation: Department of Radiology, Mount Sinai School of Medicine, New York, NY, United States.
authors.forename: David F
authors.initials: DF
authors.lastname: Yankelevitz
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D055088:Early Detection of Cancer; D005260:Female; D006801:Humans; D008175:Lung Neoplasms / Q000000981:diagnostic imaging* / Q000453:epidemiology / Q000209:etiology; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D011656:Pulmonary Emphysema / Q000000981:diagnostic imaging* / Q000453:epidemiology / Q000209:etiology; D012907:Smoking / Q000009:adverse effects*; D014057:Tomography, X-Ray Computed
keywords: CT screening; Emphysema; Lung cancer; Never smokers; Secondhand tobacco smoke exposure; Smokers