Money Matters: The Effect of Income on Postsurgical Outcomes in Stage IA Non-small Cell Lung Cancer

Treatment of non-small cell lung cancer (NSCLC) remains challenging; 5-year survival is as low as 24% for resectable disease. However, the outlook for stage IA NSCLC is favorable, with 5-year survival exceeding 74% and with surgery often being curative. Despite this positive prognosis, low socioeconomic status has been shown to correlate with nonstandard treatment and worse overall survival specifically in stage IA. This study sought to examine income-based disparities in postsurgical survival which has yet to be discussed in the current literature.

The National Cancer Database was retrospectively queried from 2004 to 2017 to identify patients with pathological stage IA NSCLC following surgical resection; survival/patient characteristics were analyzed by income quartiles and eras (2004-2007, 2008-2012, and 2013-2017). Kaplan-Meier methods and multivariable Cox hazard modeling were used to estimate survival and construct hazard ratios, respectively.

Inclusion criteria identified 138,219 patients. Overall, a stepwise decrease in 5-year survival was observed as income quartile decreased (Q4: 72.0%; Q3: 67.8%; Q2: 66.1%; Q1: 64.2%). Hazard modeling implicated income level as an independent predictor of mortality; patients of the lowest income quartile exhibited a hazard ratio of 1.26 (95% confidence interval 1.21-1.31; p < 0.001) relative to the highest. Although overall survival increased within each income quartile over consecutive eras, income-based survival disparities continued to be observed.

Lower-income patients with stage IA NSCLC display elevated mortality risk over 5 years than higher-income patients despite receiving potentially curative surgery, with income being an independent risk-factor. This difference may also be attributed to stacked risk-factors in lower-income patients.