In the present study, we applied a multiplex ddPCR-based assay to detect and quantify the seven most common hotspot mutations in codons 12 and 13 (G12A, G12C, G12D, G12V, G12R, G12S, and G13D) of KRAS in cfDNA from a large cohort of NSCLC patients, to explore the prognostic impact of KRAS G12/G13 MAF prior to first-line treatment for recurrent or metastatic disease. The gene discussed is KRAS; the disease is metastatic neoplasm.