As early as 1912, scientists had begun to suspect smoking as a factor in the increased rates of death from lung cancer, but strong retrospective and prospective studies were unavailable. Through the 1940s, prominent scientific figures continued to blame everything from improved cancer detection rates to tarred roads to industrial plant fumes as the cause of increased rates of lung cancer. While the association seems obvious to us today, there was a paucity of data to support it at that time. The ubiquity of tobacco didn’t help either. During the first half of the 20th century, nearly 80% of American men noted some amount of tobacco use. Numerous retrospective studies emerged in 1950, but there was no trump card.
Doll and Hill’s seminal study attempted a broad-based, prospective approach to address the issue. In 1951, a simple survey asking for a brief smoking history was sent to each physician practicing in the UK. Of the replies received, men under 35 and all women were excluded from the analysis, leaving approximately 24,000 men aged 35 years and above. In 1954, Doll and Hill looked at a national database to determine how many of these physicians had died and the cause of death. All 36 men who died of lung cancer were smokers. The death rate was 0.48 per 1000 for those smoking approximately 1g daily and 1.14 per 1000 for those smoking more than 25g daily. Moreover, an increase in cigarette use was directly correlated to the risk of lung cancer.
The simplicity of their study proved to be genius. There were no advanced metrics – all the data analysis can be accomplished on a basic calculator. The correlation between tobacco and lung cancer could not have been made more obvious. Unfortunately, the results did not result in rapid policy changes. A joint advertising blitz by tobacco companies left the public unaware or unconvinced of the harmful effects of tobacco for a few more decades. Still, the evidence was undeniable, and the scientific community coalesced around this body of data, widely regarded as the turning point in the war against tobacco.