Previous studies in EGFR nonselective patients revealed that patients with a higher baseline CEA level are more likely to respond to EGFR-TKIs and have longer PFS.13–15 This phenomena may be attributed to a higher EGFR mutation rate in patients with higher CEA levels.14,18 However, previous studies also revealed that higher CEA level was correlated with higher tumor burden and more advanced stage.19 Here, CEACAM5 is linked to neoplasm.