In early-stage NSCLC, the data showed that the levels of miR-182, miR-183, miR-210, miR126a, and CEA produced AUCs of 0.618, 0.648, 0.667, 0.672, and 0.676, with sensitivities of 56.3%, 78.2%, 94.3%, 56.3%, and 56.3% and specificities of 73.9%, 52.2%, 39.1%, 87.0%, and 73.9%, respectively, to distinguish NSCLC from pneumonia (P = 0.0487, 0.0182, 0.0145, 0.0006, and 0.0059; 95% CI: 0.521–0.709, 0.552–0.737, 0.571–0.754, 0.576–0.759, and 0.580–0.762; S2 Fig). This evidence concerns the gene CEACAM5 and susceptibility to pneumonia measurement.