In a retrospective study in three U.S. institutions reported in the Journal of the National Cancer Institute, Pelosof et al found that never smokers accounted for an increasing proportion of cases of non–small cell lung cancer (NSCLC) during the period from 1990 to 2013. Joan Schiller, MD, of the Inova Schar Cancer Institute, Falls Church, Virginia, is the corresponding author of this article.
The study used data from registries from The University of Texas Southwestern Medical Center, Parkland Hospital/Health Care System in Dallas (a large county charity care hospital), and Vanderbilt University for 1990 to 2013. A total of 10,593 patients with NSCLC and 1,510 patients with small cell lung cancer (SCLC) were included in the analysis.
Increased Proportion of Cases
Overall, the proportion of never-smoker NSCLC patients increased from 8.0% in the years 1990 to 1995 to 14.9% in 2011 to 2013 (P < .001), including increases from 8.9% to 19.5% (P < .001) at The University of Texas Southwestern Medical Center, 12.9% to 14.2% at Parkland Hospital (P < .001), and 1.9% to 12.9% at Vanderbilt University (P = .008). The increase was maintained in a multivariable analysis controlling for sex, stage at diagnosis, and race/ethnicity. Never smokers with NSCLC were more likely to be female vs male (17.5% vs 6.9%, P < .001), with proportions of never-smoker women and men with NSCLC increasing from 10.2% to 22.1% (P < .001) and from 6.6% to 8.9% (P = .006) over the study period. No significant increase in the proportion of cases in never smokers was observed for SCLC (from 1.5% in 1990–1995 to 2.5% in 2011–2013, P = .36) or for squamous cell NSCLC.
The investigators concluded: “This study demonstrates an increasing proportion of NSCLC patients who have never smoked in a large, diverse patient population between 1990 and 2013. Given that this increase appears independent of sex, stage, and race/ethnicity and also occurred in our county hospital, this trend is unlikely due to changes in referral patterns and suggests that the actual incidence of lung cancer in never smokers is increasing.”
The study was supported by the Simmons Comprehensive Cancer Center, the Lung Cancer SPORE, and the Margot Johnson Foundation.