Women smokers are far more likely to be killed by their habit today than they were in the 1960s, a major study has found.
The increased risk greatly outweighs improvements in medicine that have cut death rates among the majority of the population in the last 50 years.
In the 1960s, smoking raised a woman's chances of dying from lung cancer 2.7 times. By the period 2000 to 2010 this had surged to 25.7-fold higher level of risk.
A similar trend holds true for deaths from chronic obstructive pulmonary disease (COPD), another smoking-related condition.
In this case, the risk of death rose from four times greater than it was for never-smokers in the 1960s to 22.5 times.
Women smokers today start their habit earlier than they did generations ago, and until recently smoked more cigarettes per day. Tobacco use among women peaked in the 1980s, having a health impact that was felt many years later.
The study involved more than 2.2 million men and women aged 55 and older and included data spanning the period from 1959 to 2010.
Men and women who smoked in the current decade were almost equally more at risk than non-smokers of suffering lung cancer, COPD, heart disease and strokes, the research showed.
For reasons still not understood, lung cancer rates among men reached a plateau in the 1980s while the risk of death from COPD in the male population continued to increase.
The findings strongly confirm the claim that "if women smoke like men, they will die like men," say the researchers who report their findings in the New England Journal of Medicine.
Quitting smoking at any age dramatically reduces death rates from all major diseases caused by smoking, the study found.
Giving up the habit altogether was far more effective than reducing the number of cigarettes smoked. Smokers who quit by the age of 40 avoided nearly all of the excess smoking-related risk of death from lung cancer and COPD.
Paradoxically, there could be a link between higher death rates and the rise in popularity of milder "light" cigarettes, according to study leader Dr Michael Thun, from the American Cancer Society.
He said: "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.
"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."
Another study in the same journal led by Dr Prabhat Jha from the University of Toronto in Canada, found that persistent lifetime smokers lost an average of about a decade of life compared with never-smokers.
"The findings from these studies have profound implications for many developing countries where cigarette smoking has become entrenched more recently than in the United States," said Dr Thun. "Together they show that the epidemic of disease and death caused by cigarette smoking increases progressively over many decades, peaking 50 or more years after the widespread uptake of smoking in adolescence. The good news is the benefits of smoking cessation occur much more quickly and are substantial at any age."
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