Gene Variant That Cuts Lung Cancer Risk Identified
NEW YORK (Reuters Health) - New study findings show that people with a certain gene variation may have a lower risk of developing lung cancer.
``We confirmed that those with a genetic variant of the myeloperoxidase enzyme have a lower risk of lung cancer relative to those with the more common type of the enzyme,'' said lead author Dr. Brian G. Weinshenker of the Mayo Clinic in Rochester, Minnesota.
Myeloperoxidase (MPO) is an enzyme found in white blood cells that concentrate in the lungs of smokers because of inflammation, he explained. The enzyme produces substances capable of causing tissue damage. For this reason, researchers have hypothesized that the degree of MPO expression has something to do with lung cancer risk.
To investigate, Weinshenker and his colleagues evaluated the DNA of 307 patients with lung cancer and a similar group of 307 people who did not have lung cancer. The researchers were looking for a variant in the MPO gene that results in lower expression of the enzyme, and hence potentially less lung tissue damage.
Patients with two copies (one from each parent) of the genetic variant, who represent about 3% of the general population, were found to be less likely to have lung cancer, according to the report published in the January issue of the Mayo Clinic Proceedings.
``The reduction in risk in our study was most evident in those...who have two copies of the enzyme variant whose risk was reduced by 60%,'' Weinshenker told Reuters Health.
``Combining the results of our own studies with other studies reported in the literature, we concluded that having even one copy of the variant enzyme (approximately 35% of the population) reduces the risk of lung cancer, but only very slightly,'' he added.
Nonetheless, Weinshenker warns that the reduced risk of developing lung cancer seen in some people shouldn't give smokers a false sense of comfort.
``Smoking increases the risk of cancer sevenfold...so individuals with this genetic variant enzyme should not feel very secure in continuing to smoke,'' he told Reuters Health.
``There is no medical indication to have genetic testing to find out if one carries this genetic variant and is thereby partially protected from lung cancer,'' he said.
Lung cancer is the most common type of cancer in the world in terms of new cases--1.2 million, accounting for 12.3% of the world total of cancer cases--and deaths, with 1.1 million, or 17.8% of the world total of deaths from cancer.