A new study published in the Jan. 24, 2013 issue of the New England Journal of Medicine (NEJM) reveals that female smokers have a much greater risk of dying from lung cancer and chronic obstructive lung disease (COLD) in recent years than did female smokers 20 or 40 years ago. The study was conducted by Michael Thun, MD., and several colleagues, including Ross Prentice, PhD, one of the Principal Investigators of the Women’s Health Initiative. They studied smoking patterns and smoking-related deaths over a 50 year period, using data from five large studies, including the Women’s Health Initiative. In total, the study included more than 2.2 million adults 55 years and older; of those, 156,701 were WHI participants who provided updated information on smoking in 2000.
This increased risk of dying from smoking-related diseases reflects the change in women’s smoking habits. Compared with women in previous generations, women smokers today smoke more like men, that is, they start earlier in adolescence and until recently, smoke more cigarettes per day (smoking peaked in the 1980s). These findings strongly confirm the prediction that “if women smoke like men, they will die like men.”
For women who smoked in the 1960s, the risk of dying from lung cancer was 2.7 times higher than it was for women who had never smoked. In the cohort of women smokers studied from 2000-2010, the risk of dying from lung cancer was 25.7 times higher than that of never-smokers. The risk of dying from COLD for women smokers was 4.0 times higher than for never-smokers in the 1960s; the risk in the current cohort of smokers was 22.5 times higher than never-smokers. About half of the increase in risk occurred during the last 20 years. “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,” said Dr. Thun.
These findings show that disease and death caused by cigarette smoking increases progressively over many decades, peaking fifty or more years after the widespread start of smoking in adolescence. This has a profound implication for developing countries with large populations, where rates of cigarette smoking are on the rise for both men and women. In a related article in the same issue of the NEJM, Dr. Prabhat Jha and his colleagues note that based on current trends, smoking will kill 1 billion people in the 21st century, as opposed to ‘only’ 100 million in the 20th century.
A positive finding of these studies was the confirmation that quitting smoking at any age dramatically lowers death from all major diseases caused by smoking, and that quitting smoking is far more effective than reducing the number of cigarettes smoked. Smokers who quit by age 40 were found to avoid nearly all of the excess smoking-related mortality from lung cancer and COLD. “The good news is the benefits of smoking cessation occur much more quickly and are substantial at any age,” notes Dr. Thun.
Thun MJ, Carter BD, Feskanich D, Freedman ND, Prentice R, Lopez AD, Hartge P, Capstur SM (2013). 50-year trends in smoking-related deaths in the United States. NEJM, 368(4); 361-374.