Smoking causes cancer. End of story? Well, not exactly. Like everything else you're taught in grade school that seems so black and white, there are shades of gray. Turns out, some smokers are susceptible to lung cancer than others. It's all in your DNA--specifically chromosome 15.
Your DNA influences how much you smoke and whether you will develop lung cancer or chronic obstructive pulmonary disease (COPD), according to researchers led by Washington University School of Medicine in St. Louis and published in the journal Public Library of Science (PLoS) Genetics.
In what they called the first large-scale effort to match genetics with smoking, lung cancer and COPD combined, researchers studied 38,000 smokers and found that two groups of gene variants on chromosome 15 influence risk for all three problems.
Nicotine binds to nicotinic receptors in cells. Various forms of the nicotinic receptor genes were associated with how much a person smoked and, of course, heavy smokers turned out to be at greatest risk for lung cancer and COPD.
The study revealed that DNA differences on chromosome 15, particularly in the CHRNA5 nicotine receptor gene, made significant contributions to nicotine addiction, lung cancer and COPD.
"Demonstrating that all three variants are related to smoking behavior does not prove that there is a direct, biological effect linking nicotine addiction to cancer and COPD, but you certainly can't rule it out," says senior researcher Laura Jean Bierut. "It's really striking that this one gene is strongly driving addictive [behavior] and is also related to lung cancer and COPD."