Blood test may identify those at risk of lung cancer

Researchers have developed a test that could identify individuals most at risk of developing lung cancer.  Although most victims of lung cancer are smokers, only a minority of smokers develop lung cancer, suggesting that there may be a genetic predisposition to the disease.

The team, led by Professor Zvi Livneh at the Weizmann Institute, Israel, found an association between lung cancer and low levels of activity of an enzyme involved in DNA repair. Cancer is caused by damage to genes that make proteins involved in the regulation of cell division and cell death. Tobacco smoking is thought to cause an increase in DNA damage. Livneh's team compared 68 lung cancer patients with 68 healthy people. Rather than test for a specific gene, they compared the activity of a gene product, known as OGG (8-oxoguanine DNA glycosylase), an enzyme that repairs damaged DNA.

The study, published in the Journal of the National Cancer Institute, found that those with a relatively low level of OGG activity were more likely to be in the cancer group. Professor Livneh calculates that individuals with low activity of OGG are 4.8 times more likely to have cancer and that the estimated relative risk of lung cancer for smokers with low OGG activity is around 100-fold higher than for nonsmokers with normal OGG activity. He concludes '[the results] suggest that smoking cessation in individuals with reduced OGG activity might be an effective strategy in lung cancer prevention'. He added, however, that prospective large scale studies are required to validate the results. Professor Livneh was quoted in the UK's Times newspaper saying that his 'vision is that people could be screened using our test and warned if they had a high risk'.

People's variation in levels of OGG activity may have a genetic basis (the possibility that lung cancer causes a decrease in OGG activity has not yet been ruled out) and, if this is the case, and low levels do leave individuals susceptible to lung cancer, then a direct genetic test may be possible in the future.