The prognostic and predictive value of pretreatment serum levels of CEA have been assessed in advanced NSCLC patients exclusively treated with gefitinib and erlotinib and, owing that conflicting results have been reported a direct relationship between high levels of CEA and response to EGFR-TKI, however its utility has not yet been established. This evidence concerns the gene CEACAM5 and non-small cell lung carcinoma.