Gene linked to lung cancer in people who have never smoked
US scientists have identified a gene that may be responsible for a proportion of lung cancer cases among people who have never smoked.
Scientists at five centres scanned the genomes of 2,272 volunteers who had never smoked, nearly 900 of whom had been diagnosed with lung cancer.
'Never-smokers' were defined as people who smoke fewer than 100 cigarettes during their lifetime.
The researchers found that about 30 per cent of never-smokers with lung cancer had the same variation in one of their genes called GPC5.
GPC5's exact role in the body is poorly understood, but changes in the DNA where it is located are known to be common in a number of different human tumours.
Laboratory studies revealed that the genetic variation found in never smokers makes the GPC5 gene less active in lung cancer tissue compared with healthy lung tissue.
The research, which is published in the Lancet Oncology, suggests that, under normal circumstances, GPC5 may play an important role in preventing the development of tumours.
Lead investigator Dr Ping Yang, a genetic epidemiologist at Mayo Clinic, commented: "This is the first gene that has been found that is specifically associated with lung cancer in people who have never smoked.
"What's more, our findings suggest GPC5 may be a critical gene in lung cancer development and genetic variations of this gene may significantly contribute to increased risk of lung cancer. This is very exciting."
According to Dr Yang, about 15 per cent of men and 53 per cent of women worldwide who develop lung cancer have never smoked, with Asian countries having a particularly high proportion of lung cancers occurring in never-smokers.
"Our suspicion all along was that this is a distinct disease, and that is why we undertook this study," she added.
Dr Kat Arney, Cancer Research UK's science information manager, said: "Smoking causes 90 per cent of lung cancers, but there is still a significant number of non-smokers who develop the disease.
"These new results could help to explain why, but much more work needs to be done to understand exactly how these gene variations are linked to lung cancer risk."