In the validation set, there were 1/20 and 0/8 CEA‐positive, 4/20 and 1/8 NSE‐positive, and 3/20 and 1/8 CYFRA‐211‐positive patients, respectively, in the lung cancer and benign disease groups (P > 0.05 for all three biomarkers) (Table 2). This evidence concerns the gene CEACAM5 and lung cancer.