title: Differences in epidemiology, histology, and survival between cigarette smokers and never-smokers who develop non-small cell lung cancer.
abstract: BACKGROUND
  The impact that smoking cigarettes has on the characteristics and survival of patients with non-small cell lung cancer (NSCLC) is disputed.
  
  
  METHODS
  A retrospective cohort study using a prospective database of patients with NSCLC over a 6-year period. Clinical and histologic characteristics and survival rates were compared between smokers and never-smokers.
  
  
  RESULTS
  There were 730 patients; 562 patients (77%) were smokers and 168 patients (23%) were never-smokers. The overall 5-year survival rate was greater in never-smokers (64%) compared to smokers (56%; p = 0.031). Never-smokers were more likely to be younger (p = 0.04), female (p = 0.01), symptomatic at the time of presentation (p < 0.001), have poorly differentiated tumors (p = 0.04), and have a higher maximum standardized uptake value (maxSUV) on positron emission tomography (PET) (p = 0.026) than smokers. The stage-specific 5-year survival rate was greater for never-smokers compared to smokers for stage I disease (62% vs 75%, respectively; p = 0.02), stage II disease (46% vs 53%, respectively; p = 0.09), and stage III disease (36% vs 41%, respectively; p = 0.13). The 5-year survival rate was significantly lower in patients who had a smoking history of > 20 pack-years.
  
  
  CONCLUSIONS
  Never-smokers in whom NSCLC develops are more likely to be young, female, and have poorly differentiated tumors with higher maxSUV values on PET scans. Never-smokers with early-stage cancer have a significantly better survival rate than smokers. Patients with a smoking history of > or = 20 pack-years have worse survival. Thus, smoking not only causes lung cancer, but once NSCLC is diagnosed, the prognosis becomes worse. A biological, hormonal, and genetic explanation is currently lacking to explain these findings, and these data may help to improve treatment and surveillance.
authors.affiliation: Division of Cardiothoracic Surgery, University of Alabama at Birmingham, 1900 University Blvd, THT 712, Birmingham, AL 35294, USA.
authors.forename: Ayesha
authors.initials: A
authors.lastname: Bryant
authors.forename: Robert James
authors.initials: RJ
authors.lastname: Cerfolio
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002289:Carcinoma, Non-Small-Cell Lung / Q000453:epidemiology / Q000401:mortality / Q000473:pathology; D015331:Cohort Studies; D005260:Female; D006801:Humans; D015994:Incidence; D053208:Kaplan-Meier Estimate; D008175:Lung Neoplasms / Q000453:epidemiology / Q000401:mortality / Q000473:pathology; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D049268:Positron-Emission Tomography; D011379:Prognosis; D016016:Proportional Hazards Models; D012189:Retrospective Studies; D012907:Smoking / Q000009:adverse effects*