Quantitative analysis showed that the concentrations of serum CYFRA21-1 (2.65 [1.93–4.45] vs. 4.01 [2.67–8.16], P = 0.002) and SCC-Ag (0.67 [0.48–1.44] vs. 1.05 [0.63–2.31], P = 0.006) in patients with EGFR mutant NSCLC were significantly lower than those of the EGFR wild-type, while the remaining serum tumor markers (CEA, CA50, CA125, CA72-4, NSE and ferritin) revealed no significant difference between the two groups (Table 2). The gene discussed is CEACAM5; the disease is neoplasm.