Need another reason to quit smoking? This is a reasonable one - smoking causes mutations in various cells in our bodies, and not the good X-Men kind - the kinds of mutations that can continue to cause damage and encourage the development of cancer even if you quit. Cigarette smoke causes human cells to mutate up to 150 times annually, which goes a long way towards explaining how cigarettes cause cancers.

Mutated cells found in lungs, mouth, bladder, more

Mutations were found in the highest numbers in the areas smoke comes into contact with the body. Unsurprisingly, the most mutations were found in lungs, at a rate of 150 per year. The lungs were followed by the larynx and mouth in descending order.

The mutations are incidences of cancer waiting to happen, according to Dr. David Gilligan, a consultant oncologist at Papworth Hospital. “For every 150 mutations in the cell each year, that is 150 opportunities for lung cancer to develop.”

The study and its methodology

The study, Mutational signatures associated with tobacco smoking in human cancer, was published in the Science journal on November 4, 2016. It is one of the first to show exactly how cigarette smoke affects the human genome. It examined somatic mutations and DNA methylation in 5,243 cancers. A somatic mutation is a genetic alteration to a cell which can be passed on by cell division, and DNA methylation is a “switch” which controls gene expression by telling certain cells when to turn from “off” to “on”.

The study results showed that smoking increases cancer risk by increasing the load of somatic mutations. It was conducted by an international group of researchers which included the Wellcome Trust Sanger Institute in Cambridgeshire.

Is vapour from ecigs likely to do the same?

While a study of this in-depth nature has not been conducted on vapour from ecigarettes, it would be difficult to replicate the results, given that cigarette smoke contains over 43 carcinogens and over 4,000 chemicals. E cigarette vapour contains propylene glycol, vegetable glycerin, and flavourings. After a series of headlines about ecigarettes damaging cells hit the press in 2014, this New Scientist article debunked the claims that vaping was just as harmful as smoking by examining, once again, the issue of relative harm.

John Britton, a toxicologist at the University of Nottingham, said “the comparisons were based on unequal treatments, without equivalent exposures for equivalent periods of time.” Essentially, the cells were exposed to the same treatment they would receive if someone was vaping constantly for hours on end, instead of usual vaping behaviour.

Linda Bauld at the University of Stirling said of the study, “those of us reviewing the evidence are saying that when compared with tobacco smoking, e-cigarettes are a safer option, and I don’t think this new research detracts from that advice.”