Diagnostic Performance of a Multiplex Circulating Tumor DNA Assay for Lung Cancer Detection

Lung cancer remains the leading cause of cancer-related death worldwide, largely due to late-stage diagnosis. Although low-dose computed tomography (LDCT) screening can reduce mortality, it is limited by high false-positive rates, radiation exposure, and low adherence. Thus, there is an urgent need for precise, accessible, and non-invasive diagnostic alternatives. This study evaluated the diagnostic accuracy of a novel multiplexed digital droplet polymerase chain reaction (ddPCR) assay targeting hypermethylated ctDNA markers (HOXA9, OTX1, MCIDAS, SP9, and TFAP2B) in plasma for lung cancer detection. 249 patients referred for lung cancer diagnostics were prospectively enrolled, identifying 109 lung cancer cases and 140 cancer-free subjects. Participants were recruited and blood samples drawn before any clinical outcomes were known. Plasma was analyzed using a multiplex ddPCR assay for methylated ctDNA. Diagnostic performance was assessed through receiver operating characteristic (ROC) analysis and logistic regression models. The assay demonstrated an area under the ROC curve of 0.76. Sensitivity and specificity were 67.0% and 77.1%, respectively, at the sensitivity optimized cut-off. The assay performed better in late-stage lung cancers than early-stage cancers (73.1% vs. 51.6% sensitivity). Incorporating clinical characteristics improved the diagnostic model (P < 0.001) for advanced-stage disease. Thus, the multiplex ddPCR ctDNA assay may serve as a relevant diagnostic tool, complementing existing LDCT lung cancer screening.