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The 13th World Conference on Tobacco OR Health
Building capacity for a tobacco-free world
July 12-15, 2006, Washington, DC, USA
Objective: A proposed means of harm reduction is to reduce the number of cigarettes smoked per day. However, it is not clear whether this strategy decreases the risk for tobacco-related diseases. The aim is to assess the effects of smoking reduction on lung cancer incidence.
Methods: Study with up to 5 years of follow-up from the Ukrainian Centre for Prospective Population Studies. Participants were 577 men an 669 women (N = 1249) aged 19 to 75 years, who attended 2 consecutive examinations with a 2- to 5-year interval between 1997 and 2002. Participants underwent a physical examination, X-ray examination, computer tomography and completed self-filled questionnaires about lifestyle habits. The study population was divided into 6 groups according to smoking habits: continued heavy smokers (> or =15 cigarettes/d), reducers (reduced from > or =15 cigarettes/d by minimum of 50% without quitting), continued light smokers (1-14 cigarettes/d), quitters (stopped between first and second examination), stable ex-smokers, and never smokers.
Results: There were 72 incident lung cancers during follow-up. Using Cox regression, the adjusted hazard ratio for lung cancer in reducers was 0.71 (95% confidence interval, 0.52-0.97) compared with persistent heavy smokers. The hazard ratio for light smokers was 0.42 (95% confidence interval, 0.33-0.52); for quitters, hazard ratio 0.51 (95% confidence interval, 0.34-0.67), for stable ex-smokers, hazard ratio 0.16 (95% confidence interval, 0.14-0.24), and for never smokers, hazard ratio 0.09 (95% confidence interval, 0.07-0.11). Among individuals who smoke 15 or more cigarettes per day, smoking reduction by 50% significantly reduces the risk of lung cancer.