Feature Articles » Do non-smokers get lung cancer?

by Dr Leong Swan Swan

Smoking is the most important risk factor for lung cancer and accounts for up to 90% of lung cancer deaths in males and 80% of lung cancer deaths in females.

This has been linked to carcinogens (cancerinducing agents) contained in cigarette smoke, which predispose a person to lung cancer as well as other cancers like cervical cancer, esophageal cancer and cancer of the head and neck region.

Can non-smokers get lung cancer? Intuitively, they should not. However, there is a rising incidence of lung cancer among individuals who had never smoked. Our own local data published in 2006 showed that as many as 32% of lung cancers diagnosed occurred in non-smokers.

The reason why this should happen is not fully understood. Epidemiological studies suggest a possible link with passive smoking (second-hand smoke), environmental pollutants, and possibly genetic predisposition.

Lung cancers occurring in non-smokers seem to behave slightly differently. There is a higher female to male ratio, with 69% of non-smoker lung cancer patients being females compared to 12% amongst patients who smoke. The disease course and treatment options also differ from that in patients who smoke.

The survival outcome appears better in patients who are non-smokers. In addition to standard chemotherapy, a group of new therapeutic agents targeting specific aspects of cancer cells have recently been shown to be especially efficacious in Asian non-smoking patients with lung cancer of the adenocarcinoma cell type. However, there are specific tests which can better predict the suitability of using these agents in individual patients.