In the recent past, I have spent many, many hours summarising the Doctors Study, and many, many hours digging out old statistics for lung cancer deaths (and other things) for periods over 50 years ago.
I think that it is time to put it to bed because I am fed up with it!
The major thrust of Doll’s argument depends almost entirely upon the incidence of lung cancer in smokers, especially heavy smokers. Total deaths from lung cancer were 1,052 out of 25,000 deaths altogether. His figures showed that heavy smokers were twenty five times more likely to get lung cancer than life-long non-smokers. No other class of death-causing condition came anywhere near that. The nearest was COPD (Chronic Obstructive Pulmonary Disease) with about ten times the incidence (but there were only 640 deaths from COPD out of 25,000 deaths). All the other causes were around double, which does not mean very much in epidemiological terms – too many other variables.
But the biggest causes of death were heart (10,600) and stroke (3,300). Doll claimed that heavy smokers suffered twice as much as non-smokers from both of these causes of death.
The serious point that arises in my mind is this: “In 2001, when the study ended, there were still around 9,000 or the original 34,000 doctors still alive (unless they had been ‘lost’). What did the remaining doctors eventually die from?”
It is interesting to note that the original number of smokers and ex-smokers was about 27,000. By totalling the figures in Table 1 of the 2001 report, I found that about 22,400 of that 27,000 had died, leaving 4,600 still alive. There were originally about 7,000 non-smokers. By 2001, 2,900 had died, leaving 4,100 still alive.
So in 2001, there were still 4,600 smokers and ex-smokers still alive and 4,100 non-smokers still alive. By 2011, how many of those were then dead? After all, by 2011, the youngest of the original cohort would have been about 85 years old.
You might reasonably ask why Doll, Peto et al decided to stop the study in 2001. Why not continue it through to the end? Another ten years would have seen the numbers left alive reduced to a rump. It would have been very easy, and not very expensive, to simply record the deaths and their causes. In which case, we would have been able to see what eventually caused the deaths of ALL the doctors who originally enrolled in the project. This is not a trivial matter, since about 40% of the doctors were still alive in 2001. After fifty years, why terminate the project prematurely?
I cannot help but feel that it was deliberate. Doll, Peto et al did not WANT to see it through to the end. They did not WANT everyone to know that all the doctors died in the end, and that almost all died from ‘smoking related diseases’.