Smoking is a major cause of lung cancer, which accounts for 30 percent of all cancer deaths. But new research indicates that some smokers are at greater risk of succumbing to the disease than others. According to a report published today in the Journal of the National Cancer Institute, smokers carrying a newly discovered genetic marker are up to 10 times more likely to get lung cancer than those without it.

Exposure to a number of things in everyday life, from sunlight to cigarette smoke, can degrade DNA, but our bodies have developed mechanisms to mitigate this damage. Zvi Livneh of the Weizmann Institute in Israel and colleagues studied the role of a repair enzyme known as OGG1, which deletes DNA parts that have been damaged by oxygen radicals, in preventing lung cancer. The researchers found that among lung cancer sufferers, 40 percent had low OGG1 levels compared to only 4 percent of the general population. In addition, the scientists determined that smokers with low OGG1 activity were five to 10 times as likely to suffer from the disease than smokers who have normal OGG1 activity were. This risk increased to 120 times when comparing the group to non-smokers with normal levels of the enzyme.

Levels of OGG1 can be monitored using a simple blood test. The authors thus suggest that screening smokers for this new marker could provide people with a greater incentive to kick the habit.