SMOKERS will die 10 years younger on average than non-smokers, according to the largest study on the consequences of tobacco addiction.
The findings, which will be published on Tuesday, will give smokers an accurate measure of how long it will take for cigarettes to kill them.
The research, published by the British Medical Journal, is the conclusion of a 50-year project by Oxford professor Sir Richard Doll, now aged 91.
He has tracked the lives and deaths of 34,439 British doctors since 1951, when he published his seminal work establishing a definitive link between smoking and cancer.
In his latest research, he has concluded that up to two-thirds of those who smoke from youth are prematurely killed by the habit. Of those, at least one in four will die in middle age.
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More than eight out of 10 of the original group smoked but Doll and his co-researcher Sir Richard Peto, another distinguished tobacco epidemiologist at Oxford, found that giving up smoking at 30 cuts out almost all the risk of premature death, while stopping at 50 still halves the chances of dying young.
The original group were aged 21 and upwards and only a few were untraceable for the later research. Of 14,529 deemed hardened smokers in 1951, only 134 were alive in 2001.
The 1951 study confirmed the post-war observation that smokers seemed to die earlier than non-smokers and that the nicotine addiction that swept Britain from the 1920s to the 1940s was responsible for the epidemic of fatal lung cancer.
Doll gave up smoking at the age of 37, when the implications of the habit began to dawn on him. He has monitored death and disease rates in the group at regular intervals and published the results ever since he started.
Not only has the project proved that smoking is more lethal than previously thought, it has also demonstrated that the carcinogenic effects of tobacco will get everyone in the end. Whether it happens sooner or later is a matter of chance, says Doll, because it depends on a series of errors in cell replication causing the right conditions for cancer to develop.
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The results also back up studies of identical twins that found there is no such thing as the “right genes” to protect against cancer. Earlier research found that if one identical twin smokes and the other does not, the smoker will die younger.
Doll, who will give a lecture at the Royal College of Physicians on Tuesday to celebrate the achievements of clinical research sponsored by the Medical Research Council, said yesterday: “I don’t really think there is any point in doing more of this work. I don’t think there is anything more to learn.”