Female smokers have had a much greater risk of death from lung cancer and chronic obstructive lung disease in recent years than did female smokers 20 or 40 years ago, reflecting changes in smoking behavior, according to a study.
The increase in risk of death from lung cancer and chronic obstructive lung disease (COLD) in female smokers has been large enough to offset improvements in longevity from medical advances that have reduced death rates in the rest of the population over the last 50 years.
Women smokers today smoke more like men than women in previous generations, beginning earlier in adolescence and until recently smoking more cigarettes per day (with consumption peaking among female smokers in the 1980s). To find out if these changing patterns have caused womens risk to converge with that of men, researchers led by Michael J. Thun, MD, who recently retired as vice president emeritus of the American Cancer Society, measured 50-year trends in mortality related to smoking across three time periods (1959-65, 1982-88 and 2000-10), by comparing five large contemporary studies with two historical ACS cohorts. In total the study included more than 2.2 million adults ages 55 and older.
For women who smoked in the 1960s, the risk of dying from lung cancer was 2.7 times higher than that of never-smokers. In the contemporary cohorts (2000-10) the risk for smokers was 25.7 times higher than that of never-smokers. The risk of dying from COLD among female smokers was four times higher than that of never-smokers in the 1960s, and increased to 22.5 times higher in the contemporary cohort. About half the increase in risk of both conditions occurred during the last 20 years.
In male smokers, lung cancer risk plateaued at the level observed in the 1980s, while the risk of death from chronic obstructive lung disease continues to increase for reasons that are unclear. Men and women smokers in the contemporary cohorts had nearly identically higher relative risks (compared with never-smokers) for lung cancer, chronic obstructive lung disease, ischemic heart disease, stroke and other heart disease.
The research also confirmed that quitting smoking at any age dramatically lowers mortality from all major diseases caused by smoking, and that quitting smoking is far more effective than reducing the number of cigarettes smoked. The study found smokers who quit by age 40 avoided nearly all of the excess smoking-related mortality from lung cancer and COLD.
“The steep increase in risk among female smokers has continued for decades after the serious health risks from smoking were well established, and despite the fact that women predominantly smoked cigarette brands marketed as lower in ‘tar and nicotine,” Thun said in a news release.
“So not only did the use of cigarette brands marketed as ‘Light and ‘Mild fail to prevent a large increase in risk in women, it also may have exacerbated the increase in deaths from chronic obstructive lung disease in male smokers, since the diluted smoke from these cigarettes is inhaled more deeply into the lungs of smokers to maintain the accustomed absorption of nicotine.”
The study appears in the Jan. 24 issue of the New England Journal of Medicine and is available at www.nejm.org/doi/full/10.1056/NEJMsa1211127#t=article.