Smoking wipes 10 years off a person鈥檚 life on average, according to the longest ever study of smokers, but giving up at any age brings huge benefits.
Quitting at 30 virtually eliminates the risk from dying prematurely, and giving up at 50 halves it. But half of those who fail to kick the habit will die as a result of smoking, and a quarter of all smokers die in middle-age.
The results come from a 50-year update of the landmark 1954 paper which first linked smoking with lung cancer. One author of the update, published in the British Medical Journal, is Oxford University epidemiologist Richard Doll, now 91, who was a co-author of the original paper.
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By following the fate of the original 34,439 male British doctors recruited for the study in the 1950s, the update has yielded fresh insights into how smoking affects survival to middle age and beyond.
鈥淣ow, we have the lifelong story, and that鈥檚 never been available before,鈥� says Richard Peto, professor of medical statistics and epidemiology at the University of Oxford and lead author of the update. 鈥淭he bad news is that smoking is even better than we thought at killing people. The good news is that stopping smoking gives you more extra years of life than we thought.鈥�
Buying time
The gains are substantial. Stopping at ages 60, 50, 40 or 30 buys you, respectively, 3, 6, 9 or 10 years of life expectancy that would otherwise be lost to smoking-related disease.
Peto said the new study emphasised the value of giving up even relatively late in life. 鈥淵ou often hear people say: 聭I鈥檓 40 now, so it鈥檚 not worth giving up鈥�.鈥� But stopping really does work 鈥� giving up at 40 means that just one year of life is lost on average, instead of 10.
鈥淚f you enjoy life like I do, it鈥檚 damn silly to smoke because you won鈥檛 get so much of it,鈥� says Doll, who himself quit at the age of 37.
The new data show the huge impact of smoking on middle-age deaths and the way that it destroys rapid gains in health enjoyed by the non-smoking population.
A third of non-smokers born around 1915 now live to between 70 and 90, for example, compared with just seven per cent of smokers born around the same time.
Conscript generation
This generation was the hardest hit by smoking because many were introduced to free cigarettes in their late teens when conscripted to fight in the Second World War. Many continued smoking heavily, and this is borne out in the latest data.
Of the smokers in the study from earlier generations who never smoked regularly, 85 per cent reached the age of 70, for example. Yet only 57 per cent of the 鈥渃onscript generation鈥� made it to this age.
Peto says that in the half-century since Doll鈥檚 landmark paper, smoking has claimed around six million British lives. But smoking is now most popular in developing countries.
鈥淭here are 30 million new smokers each year worldwide,鈥� says Peto. 鈥淲orldwide, tobacco will soon be causing six million deaths each year.鈥�