W. Dana Flanders, Emory professor of epidemiology, and a team of ACS researchers including Michael J. Thun (first author) and Clark W. Heath Jr., reported their results in a paper published in the September issue of the American Journal of Public Health.
The study was based on Cancer Prevention Study I and II (CPS-I and CPS-II), which covered the years 1959 to 1965, and 1982 to 1986, respectively. Whites made up 97 percent and 93 percent of CPS-I and CPS-II, respectively.
"We found that premature mortality, as measured by the difference in all-cause death rates between active cigarette smokers and lifelong nonsmokers, doubled in women and continued unabated in men from the 1960s to the 1980s," the authors reported. "For men aged 40 to 69, the overall death rate was about three times higher in smokers than in nonsmokers in CPS-II, compared with twice as high in CPS-I. About half of all deaths among CPS-II smokers were attributable to cigarette smoking."
The death rates due to lung cancer increased as well, doubling among male smokers and increasing almost six-fold among female smokers from CPS-I to CPS-II. The researchers noted that the risk of death increased "despite the widespread introduction of filter-tipped, lower-tar cigarettes," which had been found to lower lung cancer risk in several studies.
The researchers also reported that "lung cancer surpassed coronary heart disease as the largest single contributor to smoking-attributable death among white middle-class smokers." However, the death rates for coronary heart disease in this nation began in the mid 1960s and the rates for stroke began falling in the 1940s; this study reflects that decline and suggests that it resulted from "factors other than smoking cessation, since mortality decreased among both current smokers and lifelong nonsmokers, groups largely unaffected by smoking cessation."
In their article, the researchers warned that since "the poor are increasingly overrrepresented among the 46 million Americans who smoke," the study may underestimate the risk of death from coronary heart disease among smokers in the general population.
-- Lorri Preston