Lung cancer in never-smokers

Never-smokers with lung cancer constitute an understudied and under-represented subset of patients. Although there have been hints that never-smokers can be afflicted with lung cancer,¹ especially among Asian Chinese women,² it is only recently that attention has turned towards this much ignored group of patients. Sparking the attention was the finding that somatic mutations of the epidermal growth factor receptor (EGFR) were consistently more common among lung tumours of never-smokers,³ and that these mutations could possibly explain the higher response rates to single agent gefitinib.^4,5 The attention was further intensified by media reports of a non-smoking wife of a celebrity who developed lung cancer.

Most studies on never-smokers with lung cancer have emerged from Asia, as the smoking prevalence rates in Asia are lower compared with the West. In Singapore, where the population is predominantly Chinese, the smoking prevalence in the general population is 24.3% in men and 3.6% in women.⁶ About 10–15% of lung cancers occur in a lifetime among never-smokers in the West,⁷ whereas about 30–40% of patients with lung cancer are never-smokers among the Asian countries.⁸ Whether this represents a higher risk of lung cancer among never-smokers in Asia or is a mere reflection of the higher numbers of never-smokers at risk is unclear at present. A recent large prospective study by Thun et al⁹ may help to put things in perspective. The study among African Americans and Whites provides estimates of mortality due to lung cancer among never-smokers, with rates of 17.1 and 14.7 per 100 000 person-years among men and women, respectively. These figures highlight that the burden of lung cancer among never-smokers is fairly significant among …