Gene Variants Linked to Lung Cancer Identified

April 2 -- WEDNESDAY, April 2 (HealthDay News) -- Scientists have pinpointed an area on chromosome 15 that has three nicotine receptor genes that appear to increase the risk for lung cancer.

This finding offers yet more evidence that lung cancer is tied to genetics and not just smoking. However, whether these gene variants represent a direct risk for lung cancer and increased susceptibility to smoking isn't clear, according to two studies published in the April 3 edition of Nature and one published in the April 2 online edition of Nature Genetics.

In the first study, researchers show a link between gene variants that increase one's affinity for smoking and the risk for lung cancer.

"We started by looking at the impact of gene variants on smoking behavior," Dr. Kari Stefansson, president of deCODE Genetics Inc., said during a Tuesday teleconference on the research.

In the study, Stefansson, looked at 14,000 smokers and found nicotine receptor genes that affect how much one smokes. These genes appear to influence the quantity of smoking as well as smoking dependence.

"In addition, we found a gene variant which confers nicotine dependence also confers a fairly substantial risk of lung cancer and peripheral arterial disease," Stefansson said. "So people who have inherited this variant from one parent have a 30 percent greater risk of developing lung cancer."

This variant is common in about 40 percent of the population, Stefansson said. "For those who've inherited the variant from both parents, their risk of developing lung cancer is 70 percent greater than those who haven't inherited the variant," he noted.

In a second study, led by Paul Brennan from the International Agency for Research on Cancer in Lyon, France, researchers looked at 11,000 people, about 4,500 of whom had lung cancer.

"Variations in the region of chromosome 15 were more common in cases of lung cancer than controls, far above what we would have expected by chance," Brennan said during the teleconference. "There was about a 30 percent increased risk for those who have one variant and about an 80 percent increased risk for lung cancer for those with two variants."