Quit cigarettes by 40 to live extra 10 years

WOMEN who smoke can increase their life expectancy by 10 years if they quit before middle age. A study of more than 1.3 million women found that stopping smoking before the age of 40 avoids more than 90 per cent of the increased risk of dying caused by continuing to smoke. Most of the increased death rate resulted from smoking-related diseases such as lung cancer, chronic lung disease, heart disease or stroke.

The risk rose steeply with the quantity of tobacco smoked, but even light smokers on fewer than 10 cigarettes a day doubled their likelihood of dying. The research, based on results from the Million Women Study, was published in The Lancet to mark the 100th anniversary yesterday of the birth of Richard Doll, one of the first people to identify the link between lung cancer and smoking. The women were recruited to the study between 1996 and 2001, at ages 50-65. They completed a questionnaire on lifestyle, medical and social factors and were resurveyed by post three years later.

The NHS central register notified the researchers when any participant died, giving the cause of death. Women were traced for an average of 12 years from the time they first joined. So far, 66,000 of the participants have died. Initially, 20 per cent of those who took part were smokers, 28 per cent were former smokers, and 52 per cent had never smoked. Those who still smoked at the three-year resurvey were nearly three times likelier than non-smokers to die over the next nine years.

The key finding was that both the hazards of smoking and the benefits of stopping were bigger than previous studies suggested. Smokers who stopped at about age 30 avoided 97 per cent of their excess risk of premature death. Although serious excess hazards remained for decades among those who smoked until 40 before stopping, the excess hazards among those still smoking after 40 were 10 times bigger. Professor Richard Peto, from the University of Oxford, a co-author of the study, said: "Smokers who stop before reaching middle age will on average gain about an extra 10 years of life."