Perhaps one of the greatest tobacco studies of all times is a prospective cohort of British male doctors (Doll et al., 2004). This study was conducted by Oxford University Professor Richard Doll, a leading cancer epidemiologist, who more than 50 years ago first reported that smoking causes lung cancer.

Recent findings show a clear picture of the risks associated with smoking. Doll and colleagues compared the hazards of cigarette smoking in men who formed their smoking habits at different periods, and the extent of the reduction in risk when cigarette smoking was stopped at different ages. Quitting at ages 30, 40, 50, and 60 resulted in 10, 9, 6, and 3 years of life gained, respectively. On average, cigarette smokers die approximately 10 years younger than do nonsmokers, and of those who continue smoking, at least half will eventually die due to a tobacco-related disease. Persons who quit before age 35 add 10 years of life and have a life expectancy similar to men who had never smoked.

Note to instructor(s): The number of years of life saved by quitting varies across studies. For example, in a CDC report (2002), it was shown that the average number of years of life lost because of smoking was 13.2 years for male smokers and 14.5 years for female smokers.
Note to instructor(s): Sir Richard Doll passed away on Sunday July 24, 2005. He was the foremost epidemiologist of the twentieth century and is best known for his research establishing the correlation between smoking and lung cancer.

“It is a rare occasion when a researcher can, within the course of his or her own lifetime, both open and close the book on a research question of such profound public health importance as the link between smoking and cancer. Sir Richard Doll's pioneering research has, perhaps more so than any other epidemiologist of his time, altered the landscape of disease prevention and consequently saved millions of lives worldwide.”
-- KS Hudmon, http://publichealth.yale.edu/news/sept05/doll.html Centers for Disease Control and Prevention (CDC). (2002). Annual smoking-attributable mortality, years of potential life lost, and economic costs—United States, 1995–1999. MMWR 51:300–303.
Doll R, Peto R, Boreham J, Sutherland I. (2004). Mortality in relation to smoking: 50 years’ observations on male British doctors. BMJ 328(7455):1519–1527.

Slide is used with permission, Rx for Change: Clinician-Assisted Tobacco Cessation. Copyright © 1999-2007 The Regents of the University of California, University of Southern California, and Western University of Health Sciences. All rights reserved.