(HealthScoutNews) -- If you knew you were genetically susceptible to smoking-related cancers, would you kick the habit?

Duke University Medical Center researchers got mixed answers when they did a study that asked that question of older, inner-city black smokers.

Those who were told their genetics put them at increased cancer risk when they smoked were no more likely to quit smoking than smokers who didn't have that genetic susceptibility, says the study, which is published in the July issue of Cancer Epidemiology, Biomarkers and Prevention journal.

The study examined 557 smokers, average age 44, with low incomes from an inner-city community health clinic.

They were divided into two groups. The first included 185 people who received nicotine replacement therapy, counseling about quitting smoking and a self-help guide to quitting smoking.

The other group of 372 people received the same services. In addition, they agreed to take a blood test for a gene called GSTM1 that's linked to increased risk of lung cancer. The GSTM1 gene creates an enzyme that detoxifies different carcinogens, including those in cigarette smoke.

Studies show that people with lung cancer are more likely to lack the GSTM1 gene. It's estimated that 35 percent of black Americans may be missing the GSTM1 gene.

The people in this study smoked an average of 15 cigarettes a day, and 59 percent of them said they tried to quit smoking within the last year. Sixty-eight percent of the study participants believed they would eventually get lung cancer if they didn't stop smoking.

Many of the people in the study already suffered adverse health effects caused by smoking.

More information

How strong is the link between lung cancer and cigarette smoking? This page from the National Women's Health Information Center states that 87 percent of all lung cancer is caused by smoking.

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