A t-test analysis of the data from all tests in this study (Table 1) revealed that the concentrations of all five tumor markers, including CEA (P <0.001), CA125 (P=0.003), NSE (P=0.023), GRP (P <0.001), and CY211 (P <0.001), were dramatically different when lung cancer tumor marker testing was performed in healthy populations versus lung cancer patients. This evidence concerns the gene CEACAM5 and lung cancer.