Effect of cigarette smoking cessation on all-cause and cause-specific mortality in US men

Background: The effect of smoking cessation on all-cause and cause-specific mortality has not been fully evaluated in long-term prospective studies of US men. Methods: 19,722 US male physicians enrolled in the Physicians' Health Study in 1982 and provided detailed smoking information in 1988 were followed until March 09, 2010. We estimated the hazard ratios (HRs) of all-cause and cause-specific death by smoking status, pack-years, and time since quitting.

Results: The mortality rates were 11.5, 16.6, and 26.1 per 1,000 person-years for never, past and current smokers. Current smokers had greater risks of death due to cardiovascular disease, sudden death (HR, 3.4; 95% CI 2.3-5.2), pulmonary disease, lung cancer, smoking-related cancers as defined by the 2004 Surgeon General's Report, colorectal (3.6; 2.3-5.7) and prostate cancer (1.8; 1.1-2.8). Compared to current smokers, past smokers within 10 years of quitting had significant reduction in mortality by 39% for all causes (0.61; 0.54-0.68), 28% for coronary heart disease (0.72; 0.52-1.01), 67% (0.33, 0.18-0.62) for sudden deaths, 49% (0.51; 0.36-0.72) for lung cancer, 41% (0.59; 0.38-0.91) for smoking related cancer, 77% (0.23; 0.10-0.51) for colorectal cancer. After 20 years of quitting, all causes and smoking-related cause-specific mortalities among past smoker were further reduced to the level of never smokers except prostate cancer which reached to risk similar to never smokers after 30+ years of quitting.

Discussions: Cigarette smoking was a major contributor to all-cause and cause-specific mortalities. The excess mortality due to smoking may be reduced rapidly after cessation.