Researchers at Duke studied more than 500 smokers in Durham. A group of 370 were tested to see if they were missing a gene that is linked to increased risk of lung cancer. The gene creates an enzyme in the body which helps detoxify the carcinogens found in cigarettes.
When the gene is missing, so is the filter and the lungs are exposed to more cancer-causing chemicals. If you have it, you can still get lung cancer.
"If you don't have that enzyme, you're sort of at a double disadvantage," researcher Collen McBride said.
McBride said many of the smokers fell into that category.
"In our case, about 40 percent of smokers were missing the gene," she said.
McBride hoped that would make them even more determined to quit.
"Unfortunately, that's not what we found," she said.
In fact, smokers who were missing the gene were no more likely to quit than those who have it. McBride said it may be because most of the participants were older and already had smoking-related health problems.
"I think in a sense, we were preaching to the choir," she said.
McBride said she believes younger smokers who feel less vulnerable to the pitfalls of smoking may respond better to the genetic testing.
While many people in the study did quit, it was credited to counseling and smoking cessation products. Study particpants were African-Americans, but at this time, researchers do not know if specific races are more likely to be missing the gene.