The largest-ever study of a million women has found that those who smoke lose a decade of their lives, while kicking the smoking habit before the age of 40 avoids more than 90 percent of the increased risk of dying caused by continuing to smoke, while stopping before the age of 30 avoids over 97% of it. The research has just been published in the online edition of the British journal The Lancet, to mark the100th anniversary of the birth of Sir Richard Doll, one of the first people to identify the link between lung cancer and smoking. A total of 1.3 million women were recruited to the study between 1996 and 2001, at ages 50 to 65 years. Participants completed a questionnaire about lifestyle, medical and social factors and were resurveyed by mail three years later.
The National Health Service’s central register notified the researchers when any participant died, giving the cause of that death.
Women were traced for an average of 12 years from the time they first joined; thus far, 66,000 study participants died. Initially, a fifth of the study participants were smokers, 28% were ex-smokers and 52% had never smoked. Those who were still smokers at the three-year follow-up survey were nearly three times as likely as nonsmokers to die over the next nine years, even though some reduced their risk by stopping smoking during this period. This threefold death rate ratio means that two-thirds of all deaths of smokers in their 50s, 60s, and 70s are caused by smoking, as most of the difference between smokers and nonsmokers came from smoking-related diseases such as lung cancer, chronic lung disease, heart disease, or stroke.