Lung cancer may run in families

Individuals who have a close relative suffering from lung cancer are at an increased risk of developing the disease, regardless of whether they smoke.

Lung cancer tops the list of the most common cancers worldwide. Tobacco smoking is undeniably the major causative factor, with long-term smokers having a 10-fold higher risk of the disease than non-smokers. Other recognised risk factors for lung cancer include exposure to radiation, asbestos and heavy metals such as arsenic, chromium and nickel.

Environmental and genetics factors are also thought to play a role. It has long been postulated that people may differ in their susceptibility to environmental risk factors and evidence is growing for a familial risk pattern.

To investigate clustering of lung cancer within families, researchers from the Institute of Cancer Research in Surrey analysed family history data on 1,482 female lung cancer cases and 1,079 similar but unaffected female controls. The investigators found a 49 percent increased risk of lung cancer among women who had a first-degree relative with the disease. The link remained even after factoring in age and cigarette smoking. The risk is even greater with early-onset lung cancer and with multiple affected family members.

Women with a close relative who developed lung cancer before 60 years of age had about a twofold higher risk of developing the disease while those having two or more relatives with lung cancer had a higher risk.

These findings support the hypothesis that genetic susceptibility to lung cancer might act as both an independent risk factor and an effect modifier of environmental risk factors.