Background: The rate of decline in lung cancer risk after smokingcessation among male population and the importance of the magnitudeof the early decline were not sufficiently defined in the earlierstudies. We evaluated the detailed duration-response relationshipbetween years since smoking cessation and lung cancer risk acrossmajor histological types in a population-based case-referent study.Methods: We recruited 1208 consecutive incident cases of primarylung cancer among Chinese males from the largest oncology centerin Hong Kong during 2004–2006, and 1069 male communityreferents frequency-matched in 5-year age groups. We performedunconditional multiple logistic regression and generalized additivemodel incorporating smoothing spline to model the potential nonlineareffect of years since cessation on lung cancer.Results: All histological types of lung cancer were strongly associatedwith current smoking. We observed a rapidly decreasing oddsratio of lung cancer (50%) across all major histological types oflung cancer (except for the large cell type) within the first 5 years ofquitting; the odds ratio continued to decrease but at a slower rate inthe subsequent years.Conclusion: The substantial benefits obtainable within a shortperiod of 5 years’ abstinence should convey an encouraging messageto chronic smokers, clinicians, and public health workers.Key Words: Lung neoplasm, Histology, Smoking cessation.(J Thorac Oncol. 2011;6: 1670–1676)
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