An article in The Guardian reports on a major investigation into root causes of cancer, and reveals how tobacco smoke mutates DNA and gives rise to more than a dozen types of tumour.

This is the first comprehensive study into the effects of smoking on human DNA.  The study, which was published in the journal Science last week, examined over 5,000 cancer genome sequences from 17 types of cancer associated with smoking.  More than 20 groups of DNA changes (mutational signatures) were found in 13 of the cancer types; however, only five of the mutational signatures were more common in smokers’ tumours.

One group of mutations, titled signature four, was found to be a key driver in lung cancer.  These mutations are believed to be caused by benzopyrene, a constituent of tobacco smoke.  The study also highlighted the effects of tobacco smoke on the bladder, kidneys and pancreas; tissues not directly exposed to smoke.

Lead author of the study, Ludmil Alexandrov, a theoretical biologist at Los Alamos National Lab in New Mexico, commented, “There is a message here for people who are occasional or social smokers who think it doesn’t do anything, …If you smoke four to five packs of cigarettes in your lifetime it doesn’t sound that much, but you still get several mutations in every cell in your lungs and these are permanent, they do not go away.”

Read The Guardian article here