title: Lung cancer decreased sharply in first 5 years after smoking cessation in Chinese men.
abstract: BACKGROUND
  The rate of decline in lung cancer risk after smoking cessation among male population and the importance of the magnitude of the early decline were not sufficiently defined in the earlier studies. We evaluated the detailed duration-response relationship between years since smoking cessation and lung cancer risk across major histological types in a population-based case-referent study.
  
  
  METHODS
  We recruited 1208 consecutive incident cases of primary lung cancer among Chinese males from the largest oncology center in Hong Kong during 2004-2006, and 1069 male community referents frequency-matched in 5-year age groups. We performed unconditional multiple logistic regression and generalized additive model incorporating smoothing spline to model the potential nonlinear effect of years since cessation on lung cancer.
  
  
  RESULTS
  All histological types of lung cancer were strongly associated with current smoking. We observed a rapidly decreasing odds ratio of lung cancer (>50%) across all major histological types of lung cancer (except for the large cell type) within the first 5 years of quitting; the odds ratio continued to decrease but at a slower rate in the subsequent years.
  
  
  CONCLUSIONS
  The substantial benefits obtainable within a short period of 5 years' abstinence should convey an encouraging message to chronic smokers, clinicians, and public health workers.
authors: School of Public Health and Primary Care, The Chinese University of Hong Kong, Shatin, China.
authors: Lap Ah
authors: LA
authors: Tse
authors: Ignatius Tak-Sun
authors: IT
authors: Yu
authors: Hong
authors: H
authors: Qiu
authors: Joseph Siu-Kie
authors: JS
authors: Au
authors: Xiao Rong
authors: XR
authors: Wang
authors: Wilson
authors: W
authors: Tam
authors: Kai Shing
authors: KS
authors: Yu
mesh_terms: D000230:Adenocarcinoma / Q000139:chemically induced / Q000453:epidemiology / Q000517:prevention & control*; D000328:Adult; D000368:Aged; D044466:Asian People; D018287:Carcinoma, Large Cell / Q000139:chemically induced / Q000453:epidemiology / Q000517:prevention & control*; D002289:Carcinoma, Non-Small-Cell Lung / Q000139:chemically induced / Q000453:epidemiology / Q000517:prevention & control*; D002294:Carcinoma, Squamous Cell / Q000139:chemically induced / Q000453:epidemiology / Q000517:prevention & control*; D016022:Case-Control Studies; D005500:Follow-Up Studies; D006723:Hong Kong / Q000453:epidemiology; D006801:Humans; D015994:Incidence; D008175:Lung Neoplasms / Q000139:chemically induced / Q000453:epidemiology / Q000517:prevention & control; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D012307:Risk Factors; D055752:Small Cell Lung Carcinoma / Q000139:chemically induced / Q000453:epidemiology / Q000517:prevention & control*; D012907:Smoking / Q000009:adverse effects; D016540:Smoking Cessation