Sir Richard Doll: The doyen of the world's epidemiologists, Sir Richard Doll, who has died aged 92, proved the link between lung cancer and tobacco smoking.
He hit the headlines in 1950 when, with Sir Austin Bradford Hill, he shattered government and public health complacency with research among patients in 20 London hospitals. Over three decades the registrar general's records had shown a very rapid and unexplained increase in lung cancer deaths among men. The search, involving patients with and without lung cancer, had no obvious causes to target. The prime suspects were the smuts from coal fires, exhaust fumes from cars and tarring of the roads.
Doll, working with Bradford Hill, recorded the lifestyle and habits of men admitted to London hospitals with suspected lung cancer. Later, after the patients had a diagnosis, he found that those whose suspected lung cancer was confirmed were the smokers, and those in whom lung cancer was ruled out were the non-smokers.
Within a few months, cigarette smoking, then believed to be generally harmless apart from "smoker's cough", had emerged unambiguously as the only dominant factor - so dominant as to seem causal.
Yet publication of this crucial Medical Research Council (MRC) study, which was completed in 1949, was delayed for a year at the insistence of Sir Harold Himsworth, then the council's secretary. He felt that the findings were so important and unexpected they should not be released until they had been confirmed by a second study embracing hospitals around the country.
Doll and Bradford Hill quickly confirmed that cigarette smoking was the single and overwhelmingly most powerful connection with lung cancer. A preliminary study along the same lines also appeared in the United States, so the MRC team could not claim the priority their work deserved.
A former smoker, Doll gave up when he saw his research results. He also showed that smoking caused premature death from cardiovascular disease, and that a bland diet was of no benefit to people suffering from peptic ulcers, thus releasing them from a dull and pointless regimen.
He did major work on the safety of the contraceptive pill, and showed that low-level radiation, as exemplified by the useless radiotherapy given to men with ankylosing spondylitis, caused a dose-related leukaemia.
As he aged, his autocratic perfectionism led to conflicts with many scientists and medics, who wanted quicker answers than Doll could allow on available information - such as his uncertainty until 1993 about increased child thyroid cancer after Chernobyl.
However, what he questioned, quite properly, was the quality of the underlying information. This conservative caution did not in fact reflect a political conservatism, for Doll and his wife were both quite left wing early on and were associated with various progressive causes.
Environmental pressure groups thought him so dismissive of early evidence or of a small number of cases as to be defending the interests of government and industry. Yet, as Doll pointed out, the mathematics of statistical studies is uncertain.
One of his earliest papers, published in 1936, showed that many medical decisions at the time were based on studies of groups of patients so small as to be statistically meaningless. In the 1950s, Doll and Bradford Hill launched a long-term prospective study of the effects of smoking on British doctors (a group of about 20,000), which confirmed the lung-cancer connection.
It also showed how risk related directly to the extent of smoking and how chronic bronchitis and coronary disease were also, according to this and other studies, caused by smoking.
Doll was more aware than many of his critics that an association, however powerful, does not necessarily imply causation. He never claimed a causal relationship between smoking and lung cancer on the basis of the first case-control studies or of the prospective study. Only when all other available information was brought into the picture did he feel that a true causal relationship had been shown.
His assessment included the historical sex-ratio difference of smoking and of later disease, the absence of any increase in lung- cancer deaths in countries where smoking was rare or had started late (such as Iceland and Norway), and the rapid increase of lung cancer incidence in countries where smoking had started early.
However, even when it was shown that all populations with a long smoking history suffered a large increase in lung cancer, yet nowhere was there a high incidence of lung cancer among non-smokers, the causal relationship continued to be challenged.
In Britain it took a quarter of a century before tobacco was taxed on health grounds, but Doll was disappointed in later years by a worldwide failure to ban tobacco advertising. From the early 1950s he argued that the need was not to convert addicts, but to prevent children starting to smoke.
The tobacco problem remained Doll's main concern until the end of his life, but he also studied industrial causes of cancer, domestic dangers such as radon in houses, and the problems of low-level radiation exposure for the general population.
Patrician in bearing and often sharply critical, Doll could be formidable but he relaxed easily and had a great sense of humour. He enjoyed explaining how, had it not been for too much ale on the night before a scholarship paper, he might have been a mathematician. He failed the scholarship and was offered an exhibition.
"The beer I had that night was the best drink I ever had," he later joked. "I decided to go into medicine and I have enjoyed every minute since."
He had always admired his father's work and dedication as a GP in London and, in the event, went from Westminster School to St Thomas's, graduating in 1937. After a year as casualty officer and house physician at St Thomas's, he was called up for service in the second World War, and served in France and the Middle East. His diary as a battalion medical officer of the retreat to Dunkirk, terse, observant and shrewdly aware of tragi- comedy, was published in the British Medical Journal in 1990.
He described life on a hospital ship in the Mediterranean during the north African and Italian campaigns as "the happiest years of the war", largely because Rommel and German U- boat commanders paid full respect to the Red Cross on the high seas, provided the hospital ships sailed under full lights.
In 1944 he came home as an invalid with a tubercular kidney. After discharge and some disappointment, he approached the MRC, and through Dr Joan Faulkner (whom he married shortly afterwards; they had a son and a daughter) found a research post at the Middlesex Hospital, studying occupational factors in the development of gastric and duodenal ulcers.
This launched both his glittering career and a lifelong powerful marriage. Within a year he joined Bradford Hill in developing ways of improving epidemiological techniques. Thirty years later, honoured throughout the world, he was still modestly seeking better ways of unravelling the connections between lifestyle, occupational exposures and disease.
Doll remained mentally alert, academically productive and in good health until his death. His wife died in 2001. He was made regius professor of medicine at Oxford University in 1969, retiring in 1979, was knighted in 1971 and became a Companion of Honour in 1996.
William Richard Shaboe Doll: born October 28th, 1912; died July 24th, 2005.