Women who smoke are now far more likely to be killed by their habit than they were in the 1960s, a major US study has found.

The increased risk in these women - partly a result of changing smoking habits - outweighs improvements in medicine that have cut overall death rates the last 50 years.

In the 1960s, women in the US who smoked were almost three times more likely to die from lung cancer than women who had never smoked. This surged to almost 26 times the risk between 2000 and 2010. A similar pattern is seen for another smoking-related disease called chronic obstructive pulmonary disease (COPD).

The increased impact of smoking is in part down to the fact that women today generally start their habit earlier - so have been smoking for longer.

Changing smoking habits may also play a part, as people today tend to smoke cigarettes designed to promote deeper inhalation.

The study involved more than 2.2 million men and women aged 55 and older and included data from 1959 to 2010.

Daily cigarette smoking in men peaked in the 1970s, whereas it did not peak until the 1980s in women. This is why it is only now that women's risk from smoking is starting to match that of men.

The findings strongly confirm the claim that "if women smoke like men, they will die like men," say the researchers, led by Dr Michael Thun from the American Cancer Society.

Another study in the same journal - the New England Journal of Medicine - found that persistent lifetime smokers lost an average of around a decade of life compared with people who had never smoked.

But the study, led by Dr Prabhat Jha from the University of Toronto in Canada, also confirmed that quitting smoking at any age reduces death rates from all major diseases caused by smoking. And 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.

Claire Knight, health information manager at Cancer Research UK, said: "These studies add to the huge body of evidence from over 50 years of research showing the dreadful toll smoking takes on your health. Smokers lose an average of 10 years of their life so, if you're a smoker, the best thing you can do for your health is to quit.

"It's never too late to stop smoking, but the sooner you do, the more of those years you could get back."

Source: CRUK