The irony of “not caring” about the effects of e-cigarettes on smoking-related cancer deaths


By Dr Farsalinos

A paper was published yesterday in Tobacco control estimating the cancer risk potency of electronic cigarettes. In my opinion, this was a good exercise but a premature one, mainly because for some strong carcinogens (such as 1,3-butadiene, which is considered the compound with the highest contribution to cancer risk from smoking) we have no data concerning e-cigarette emissions. However, I am convinced that, even when we have data, the estimated cancer risk from e-cigarette use will be less than 1% of the respective risk from smoking.

This comment however is more focused on an unbelievable claim that determining the cancer risk of e-cigarettes is asking the wrong question!! This unimaginable statement is not only inhumane but it is also totally unscientific and contrary to any available data. For start, it is (once again) based on the flawed argument that the “particulate matter” in e-cigarettes increases the risk of cardiovascular disease. I have discussed about this previously here and here. Ignoring the humanitarian aspect of the statement, let’s look at the data to prove how wrong this statement is. I did some rapid calculations using data from the 2014 Surgeon General Report on annual tobacco-related deaths for 2005-2009 (presented in a nice table in the CDC website) and the CDC report on causes of death for the general population for 2014. To clarify, cause of death in smokers as reportedin the Surgeon General report do not include unrelated to smoking factors like accidents, suicides, Alzheimer’s disease etc. Therefore, I used the sum of deaths from cardiovascular/metabolic disease (including strokes and diabetes), lung disease (including pneumonia and influenza) and cancers as 100%, and then I calculated the proportion of deaths from each of these causes. Additionally, it should be noted that second-hand smoking-related deaths are deaths of non-smokers, so these deaths were included into the non-smokers group. I was able to calculate deaths and % of deaths separately for non-smokers by subtracting total population deaths from smokers’ deaths. Finally, the death rates were calculated (number of deaths per 100 people, presented in % - multiply the number by 1000 to generate the number of deaths per 100,000 people) considering the total US population of 318.6 million (2014 data). Finally, the number of smokers was estimated at 48 million.

Below are the number of deaths from the 3 main causes for the total population, the smoking population and the non-smoking population (which includes deaths from second-hand smoke).

death rates1.jpg

As you can see, in the population of non-smokers, cardiovascular/metabolic disease accounts for 55.1% of deaths annually. Of course, it is common knowledge that in the developed world the majority of deaths are caused by cardiovascular disease. Therefore, if all smokers were non-smokers, 55.7% of their deaths annually would have been caused by cardiovascular disease. The same proportion would have died from cancers, while a strong reduction would have been observed in the proportion of deaths from lung disease. Does this mean that, if smokers were non-smokers, more would have died from cardiovascular disease? Of course not, because these numbers are proportions of all deaths and not proportion of the total population dying annually. By looking at the death rates and using the same death rate as non-smokers (excluding second-hand smoking deaths, i.e. the last column of the table above), we can calculate how many smokers would die from each cause if they were non-smokers, and how many deaths would have been saved. Here it is:

death rates2

The results are pretty obvious and show that substantially more deaths from cancer and lung disease compared to cardiovascular disease would have been prevented if smokers were non-smokers. These calculations not only reject the previously mentioned statement (which is fundamentally problematic, to say the least) but clearly show that it is absolutely crucial to assess the effect of switching from smoking to e-cigarette use on all disease conditions. More deaths will be prevented through reductions in lung disease and cancers compared to reductions in cardiovascular/metabolic disease.




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