Smokers die 10 years younger, according to long-term study

On average cigarette smokers die 10 years younger than non-smokers, but stopping at age 50 halves the risk, and stopping at 30 avoids almost all of it, according to a 50-year-long study of smoking and death among British doctors, published in this week's British Medical Journal (BMJ).

Sir Richard Doll, emeritus Professor of Medicine at the Clinical Trial Service Unit (CTSU), University of Oxford, launched the study in 1951 when he himself was in his 30s. The initial results, confirming the link between smoking and lung cancer, were published in the BMJ on 26 June 1954. Exactly 50 years later, and now in his 90s, he reveals the final results in this week's BMJ.

The main findings show that the overall risks are much greater than originally suspected: at least half, and perhaps as many as two thirds, of all persistent cigarette smokers from youth are eventually killed by their habit, and about a quarter are killed while still in middle age (35-69); longevity has been improving rapidly for non-smokers, but not for those who continue to smoke; on average, cigarette smokers die about 10 years younger than non-smokers; and stopping at ages 60, 50, 40 or 30 gains, respectively, 3, 6, 9 or 10 years of life expectancy.

The study, funded by the UK's Medical Research Council, Cancer Research UK and the British Heart Foundation, monitored the long-term smoking habits of 34,439 male doctors born between 1900-1930.

The last questionnaire was sent to survivors in 2001, making these men the first population in the world in which the full hazards of long-term cigarette smoking, and the corresponding benefits of stopping, can be assessed directly.

Among the doctors born 1900-1930, about half of the cigarette smokers were killed by their habit. However, there was a unique group of men born around 1920 who faced even worse odds. Smoking killed two-thirds of those who continued to smoke cigarettes.

The study authors attribute the peculiarly high risk for this particular generation to conscription into the British army from 1939 onwards. The armed forces provided low cost cigarettes to conscripts, which established the addiction with an intense early exposure to smoking.

However, the study also demonstrates the benefits of quitting at any age.

Sir Richard Doll said: "Over the past few decades, prevention and better treatment of disease has halved non-smoker death rates in the elderly in Britain. But these improvements have been completely nullified by the rapidly increasing hazards of tobacco for those who continue to smoke cigarettes."

Dr Richard Smith, BMJ Editor, said that the study was a "remarkable achievement".

(gmcg)