Clinical Utility of Next-Generation Sequencing in Tumors Diagnosed as Lung Squamous Cell Carcinoma: Real-World Data of Diagnostic and Therapeutic Implications.

Abstract

Lung squamous cell carcinoma (LUSC) is the second most common subtype of non-small cell lung carcinoma (NSCLC), typically associated with a poor prognosis. Unlike lung adenocarcinoma, the application of next-generation sequencing (NGS) in LUSC has lagged because of the long-standing perception of low therapeutic yield, primarily based on highly selected, resected cohorts. We sought to determine the real-world clinical utility of NGS in LUSC. We analyzed an institutional cohort of 576 tumors initially diagnosed as LUSC that underwent NGS profiling. We defined "clinical yield" as either diagnostic reclassification or the identification of a targetable mitogenic alteration. Twenty cases (3.5%) were reclassified, including rediagnosis to cutaneous squamous cell carcinoma, transformed adenocarcinoma (post targeted therapy), and rare entities such as nuclear protein of the testis-rearranged carcinoma and lymphoepithelial carcinoma. Primary mitogenic drivers were identified in 83 cases (14.4% of the total cohort), of which 43 (7.5% of the total cohort) harbored alterations with currently Food and Drug Administration-approved therapies for NSCLC (including KRAS, EGFR, MET, ALK, and ROS1). Overall clinical yield-defined as the sum of diagnostic reclassifications and identification of NSCLC-specific targetable alterations-was 11.0% (63/576). Univariate and multivariate analysis demonstrated that never or light smoking history was the strongest independent predictor of clinical yield, with 57.3% of tumors in this subset being reclassified or harboring a strong driver. Our findings demonstrate that NGS provides significant diagnostic and therapeutic value in a real-world LUSC cohort, challenging the historical premise of low yield. Although clinicodemographic features can help prioritize testing in resource-limited settings, the identification of targetable drivers across all smoking groups supports the universal application of comprehensive NGS for all patients diagnosed with LUSC.