D’Antona P, Cattoni M, Dominioni L, et al. - Given the inconsistent nature and difficulty in the replication of the published circulating miRNA signatures introduced for early-stage non–small cell lung cancer (NSCLC) detection, researchers employed droplet digital PCR (ddPCR) technique in an Italian cohort of 75 patients with stage I–II NSCLC and 111 tumor-free controls to measure serum level of miR-223 and miR-29c, rising from published studies, respectively, as a highly sensitive and a highly specific biomarker of early-stage NSCLC. The training set included 40 stage I–II NSCLCs and 56 controls. An AUC of 0.753 and 0.632 was generated for miR-223 and miR-29c, respectively, for identifying NSCLC, in the training set. An AUC of 0.750 was generated when miR-223 was combined with miR-29c, which did not improve over that of miR-223 alone. In this study utilizing ddPCR technology, external validation was gained for miR-223 as a reproducible, effective serum biomarker of early-stage NSCLC in ethnically diverse people. The miR-223 diagnostic performance was not improved when combined with miR-29c.