The increasing challenge of never smokers with adenocarcinoma lung: Need to look beyond tobacco exposure

Lung cancer continues to remain as one of the leading causes of morbidity and mortality worldwide, despite the decreasing trends in smoking prevalence worldwide. An earlier study from the authors' institute reported the increasing trends of "Nonsmoking associated lung cancers." All consecutive histologically confirmed patients with lung cancer who presented to the outpatient department over a year (November 2014-October 2015) were included in this current prospective study. Seven hundred and thirteen patients presented with clinicoradiologically suspicious findings of lung cancer in the said period. A pathological confirmation of lung cancer could be ascertained in 495 patients, and this cohort was further analyzed. The mean age of presentation was 57.76 years; the male to female ratio was approximately 2.5:1. Interestingly, 55.35% of the patients were nonsmokers. Adenocarcinoma (63%) was the predominant histology. Never smokers, both among men (P = 0.02) and women (P = 0.001), presented more frequently with adenocarcinoma histology. Further, 84.9% (45/53) of rural and 76.1% (19/25) of urban women who were never smokers reported exposure to indoor air pollution (secondhand smoke/fuel used for cooking purposes) which was significantly associated with adenocarcinoma histology. Our study confirmed our initial observation of the changing epidemiology of lung cancer in the Indian subcontinent, paralleling the global trends of rise in adenocarcinoma. Lung cancer in never smokers outnumbering that among smokers was another interesting observation. The take-home message for both the clinicians as well as the policymakers is to study factors beyond tobacco exposure to understand the direction of the current lung cancer epidemic.