Molecular Biomarker and Programmed Death-Ligand 1 Expression Testing in Patients With Advanced Stage Non-small Cell Lung Cancer Across North Carolina Community Hospitals

Abstract

Background: Precision medicine in advanced non-small cell lung cancer (NSCLC) requires molecular biomarker testing in patients with nonsquamous and select patients with squamous histologies, and programmed death-ligand 1 (PD-L1) testing in both.

Research question: What are rates of molecular and PD-L1 biomarker testing in patients with advanced NSCLC in community practices, and do rates vary by sociodemographic factors? What is the prevalence of molecular biomarker mutations and PD-L1 expression levels?

Study design and methods: From 389 stage IV NSCLC pathology reports obtained through the University of North Carolina Lineberger Comprehensive Cancer Center's Rapid Case Ascertainment Program from 38 community hospitals across North Carolina, we abstracted demographics, histology, molecular biomarker testing and results, and PD-L1 testing and expression. We geocoded patient and hospital addresses to determine travel time, distance to care, and census block level contextual variables. We compared molecular biomarker and PD-L1 testing rates, the prevalence of molecular biomarkers, and PD-L1 expression levels by race and sex, using χ² tests. We determined predictors of testing, using multivariable logistic regression and report adjusted ORs and 95%CI.

Results: Among patients with nonsquamous NSCLC, 64.4% were tested for molecular biomarkers, and among all NSCLC patients 53.2% were tested for PD-L1 expression. Differences in biomarker testing rates by sociodemographic factors were not statistically significant in univariate or adjusted analyses. Adjusted analyses showed that patients living in areas with higher household internet access were more likely to undergo PD-L1 testing (adjusted OR = 1.66, 95% CI, 1.02-2.71). Sociodemographic differences in molecular biomarker prevalence and PD-L1 expression levels were not statistically significant, except for human epidermal growth factor receptor 2 (HER2) mutations, which occurred in 16.7% of males vs 0% in females, P = .05.

Interpretation: Biomarker testing remains underused in NSCLC. Future work should include larger populations and evaluate hospital-specific testing protocols to identify and address barriers to guideline-recommended testing.

Keywords: PD-L1; molecular biomarkers; non-small cell lung cancer.