Smoking and lung cancer consensus

Summary

• Smoking is now one of the best established causes of disease in medicine, but when the first strong evidence appeared most experts doubted it. Many put the rise in lung cancer down to better diagnosis or to air pollution from cars, tarred roads and coal fires.
• In 1950 Richard Doll and Austin Bradford Hill compared 649 men with lung cancer with 649 men in hospital for other illnesses. Only 2 of the cancer patients had never smoked, against 27 of the others, so they concluded that smoking was an important cause.
• The doubt was about the kind of evidence. Nobody could ethically make people smoke for a trial, and watching people shows that two things go together without proving that one causes the other. The statistician Ronald Fisher argued in 1958 that genes might lead to both smoking and cancer.
• Tobacco companies worked to keep that doubt alive.
  • In January 1954 American tobacco companies ran an advert in more than 400 newspapers saying "We believe the products we make are not injurious to health", and set up the Tobacco Industry Research Committee to fund research.
  • Three British scientists visited the American industry in 1958 and reported that the researchers they met, with one exception, already believed smoking was an essential link in the chain leading to lung cancer.
  • An undated internal memo from the company Brown & Williamson said "Doubt is our product", because doubt was the best way to compete with the facts in the public's mind.
• Governments accepted the link in stages.
  • In February 1954 the Minister of Health, Iain Macleod, told Parliament that his advisers saw a strong presumption that the link was causal, but that there was no firm evidence of how smoking caused cancer. He also announced £250,000 from the tobacco companies for research.
  • The Royal College of Physicians, which speaks for hospital doctors, set out the case in a report on 7 March 1962. The health minister, Enoch Powell, then told Parliament that it proved the causal connection.
  • The US Surgeon General, the government's chief doctor, named cigarettes a cause of lung cancer on 11 January 1964.
• In 2006 a US federal judge found that the big tobacco companies had known many of the facts about smoking's harm for at least 50 years and denied them to the public. In the UK 9.8% of adults smoked in 2025, and smoking is still linked to about 80,000 deaths a year.

Dig deeper

• Most of the people judging the evidence smoked themselves. Over 80% of British men smoked after the Second World War, and in 1962 70% of men and 43% of women still did. Macleod chain smoked through the press conference at which he announced the link.
• Doll and Hill began following 34,439 male British doctors in 1951. After 50 years, the men who kept smoking cigarettes had died about 10 years younger than those who never smoked, and stopping at 30 avoided almost all of the extra risk.
• In 1965 Bradford Hill listed what should persuade a doctor that an association is a cause, such as its strength and whether more exposure brings more disease. Smokers died of lung cancer nine to ten times as often as non smokers. He added that incomplete science gives no one "a freedom to ignore the knowledge we already have".
• Fisher was a consultant to the Tobacco Manufacturers' Standing Committee, an industry body, in the late 1950s. A 1991 paper defending him argues that his letters show real concern about misleading consumers with a statistical result, and his motives are still disputed.
• The 1962 report made seven recommendations to government, and the immediate result was a £50,000 publicity campaign and the first stop smoking clinics.
  • Tobacco tax was 14% of public revenue, and the Treasury refused a large tax rise because it would "heavily penalise" poorer smokers.
  • Some saw the doctors' campaign as an attack on freedom. When the College reported again in 1971, a Daily Telegraph columnist wrote that it was "taking the place of the Church as the main threat to human freedom".
• The same argument over how much evidence is enough now arises with vaping. The Tobacco and Vapes Act 2026 will stop anyone born on or after 1 January 2009 from ever buying tobacco.

Ethical issues

Interview questions

• What do you know about how smoking came to be accepted as a cause of lung cancer?
• No trial has ever made people smoke. How can doctors be confident that smoking causes cancer?
• Why did it take until the 1960s for governments to accept fully that smoking causes lung cancer?
• A patient tells you his grandfather smoked 40 a day and lived to 95, so the risks are exaggerated. How do you respond?
• What are the arguments for waiting for more evidence before warning the public about a risk, and the arguments against?
• How should a doctor judge research paid for by a company that sells the product being studied?
• Should the money a government earns from a product affect how it regulates that product?
• Which health risk today might future doctors look back on the way we look back on smoking?