October 29, 2012
Women Who Quit Smoking Before Age 40 Reduce Risk Of Death By A Decade
Lawrence LeBlond for redOrbit.com - Your Universe Online
People who are able to kick the habit are undoubtedly reducing the risk of a trove of health issues and an early death. And now, the largest-ever study of smoking among women in the UK has shown the female smokers who quit before the age of 40 can add up to an extra decade to their lifespan.
The study, led by Sir Richard Peto of Oxford University, shows that women smokers who give up the habit before age 40 have a 90 percent reduced risk of smoking-related death, and quitting by age 30 reduces that risk by 97 percent.
The researchers, conducting the study on more than 1.3 million female smokers, show that those who continue to smoke their whole life died on average 10 years earlier than those who never picked up the habit. For those who quit smoking at age thirty lose an average of a month of life and those who quit at forty lose a year.
Further, Peto and his colleagues found that two-thirds of all deaths of smokers in their 50s, 60s and 70s are due to smoking-related diseases. Most of the increased death rate resulted from diseases including lung cancer, chronic lung disease, heart disease and stroke.
The risk of smoking-related disease and death rose sharply with the amount of tobacco smoked, but even those who smoke less than 10 cigarettes per day double their likelihood of dying.
“Smokers lose at least 10 years of lifespan. Although the hazards of smoking until age 40 years and then stopping are substantial, the hazards of continuing are 10 times greater,” wrote the researchers in a paper published in the journal The Lancet just one day before the 100th anniversary of the birth of Sir Richard Doll, who became the first to establish a link between smoking and lung cancer.
For the study, the researchers enrolled women aged 50 to 65 over five years from 1996 to 2001 and investigated the links between health and lifestyle. Participants in the study completed a questionnaire about their living habits, medical and social factors and were re-surveyed three years later. Women were monitored for 12 years on average, during which there were 66,000 deaths.
Initially, 20 percent of the women accepted into the study were smokers, 28 percent were ex-smokers, and 52 percent had never smoked before. Those who still smoked at the three year follow-up were nearly three times as likely to die over the next nine years.
The researchers said they had found that both smoking hazards and cessation benefits were greater than previous studies had suggested.
Because men historically began smoking earlier than women, the life-shortening impact cigarettes have on them has not been fully measurable until recently. Most of the first-generation of women with lifelong smoking habits were born in the 1940s.
“If women smoke like men, they die like men - but, whether they are men or women, smokers who stop before reaching middle age will on average gain about an extra 10 years of life,” said Peto.
“Both in the UK and in the USA, women born around 1940 were the first generation in which many smoked substantial numbers of cigarettes throughout adult life. Hence, only in the 21st century could we observe directly the full effects of prolonged smoking, and of prolonged cessation, on premature mortality among women,” Peto noted in a press release.
The researchers noted that the age at which women began smoking was also important. Picking up the habit at an early age increased the length of time for which they smoked and the greater risk for an early death. Women now are starting to smoke at an even earlier age, which will further increase the likelihood of premature death.
“In those days smokers were starting in late teens and now it is in their early teens,” said Peto.
Doll, who died in 2005 at 92 years old, carried out lifelong research into the associations of lung cancer to smoking. Peto, who worked with Doll for 30 years, said that Doll´s work has helped prevent millions of premature deaths worldwide.
Doll showed in 1950 that smoking was “a cause, and an important cause” of the rapidly increasing epidemic of lung cancer in the UK.
Referring to the Million Women Study, Peto said it had allowed unprecedented insights into women´s health prospects and could only have been carried out in the UK.
“It is completely brilliant because the NHS health records are so brilliant. You couldn't do it in any other country in Europe. We can send details of the women to the NHS central register and we get told what everybody died of. Every time they go to hospital, we know about it,” said Peto.
Sir Richard Doll´s centenary is being marked by a scientific meeting held at Oxford next week. Leading researchers from around the world will gather to discuss the latest findings from several large-scale studies from across the globe.
The research was conducted by the Million Women Study Collaborators led by Oxford University researchers in the Cancer Epidemiology Unit and the Clinical Trial Service Unit. The Million Women Study is funded by Cancer Research UK, the Medical Research Council, and the Health and Safety Executive.