Smoking is more dangerous than previously thought but the benefits of giving up are much greater than expected, according to a study of 1.3 million women.
Those who give up smoking before the age of 30 can avoid 97 per cent of the health risks associated with the habit, researchers say. Even giving up before 40 cuts the risk by 90 per cent.
But women who don’t give up and continue smoking into middle age lose at least 10 years of life.
The study, by researchers at Oxford University, is published to mark tomorrow’s 100th anniversary of the birth of Sir Richard Doll, the physician who arguably has saved more lives than anyone else. He was the first, with his colleague Austin Bradford Hill, to make the link between smoking and cancer in the early 1950s, when four out of five men and two out of five women in the UK smoked. Now, thanks to campaigns highlighting the risks of smoking, the proportion is down to one in five in both sexes. Even so, smoking remains the leading preventable cause of death in the UK, US and other countries.
The findings, from the Million Women study published in The Lancet, show that smokers who continue with the habit after 40 have 10 times the risks of those who stop at 40. The risks are highest among the heaviest smokers, but even light smokers, who consume between 1 and 9 cigarettes a day, have twice the risk of dying prematurely compared with non-smokers.
Although the figures are drawn from women smokers, experts said men faced a similar risk.
Women took up smoking much later than men, peaking in the 1960s, and because there is a 30-year time lag before the habit is reflected in mortality rates, deaths among women linked to smoking are rising even though the popularity of smoking has declined.
The key message is that even though excess risks linked with smoking continue for decades after stopping, it is never too late to stop.
Sir Richard Peto, co-author of the study from the University of Oxford and who worked with Sir Richard Doll for many years, said: “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.” He added: “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.”
When Sir Richard Doll published his groundbreaking study linking smoking with cancer in 1950 the response was sceptical. Smoking was respectable and the tobacco industry was a major contributor to the Treasury. Ian Macleod, the health minister, waited four years before holding a press conference on the findings – and smoked throughout.
Smokers and the tobacco companies are now in retreat. Because of that early warning, published in the British Medical Journal on 30 September 1950, and the campaigns that followed, millions of lives have been saved.