EGFR and lung cancer: Previous studies revealed that CEA response after operation and response to chemotherapy were prognostic factors in patients with NSCLC.13,35,36 Previous studies also revealed that normalization of CEA after surgery was a prognostic factor in patients with early-stage gastric, rectal, and lung cancer.37–39 However, the impact of CEA trend and normalization in patients treated with EGFR-TKIs is not well known.