CEACAM5 and non-small cell lung carcinoma: In clinical application, serum tumor biomarkers can be used as prognostic indicators in NSCLC.31, 32 Chiu et al33 revealed that changes of CEA, CA125, and CA19‐9 levels at 4 weeks after treatment with gefitinib can predict the survival of patients with advanced NSCLC, and unexpectedly, the authors found no correlation between CEA and OS or PFS.