CEA serum level as early predictive marker of outcome during EGFR-TKI therapy in advanced NSCLC patients

Considering the role of carcinoembryonic antigen (CEA) serum levels as potential useful predictive marker during chemotherapy treatment, we studied its applicability in advanced non-small cell lung cancer (NSCLC) patients treated with epidermal growth factor receptor (EGFR) tyrosine-kinase inhibitors (TKIs). Our retrospective cohort consists of 79 patients (33 EGFR mutated and 46 EGFR wild type or unknown) affected by advanced NSCLC, for whom CEA serum values at the beginning of TKI therapy and after the first month of treatment were available, regardless of treatment line. Baseline CEA value, percentage of CEA reduction after 1 month, and percentage of patients with ≥20 % CEA decrease after 1 month (CEA response) were correlated with disease control rate (DCR), progression-free (PFS), and overall (OS) survival, according to EGFR mutational status. Median baseline CEA levels were significantly higher in EGFR mutated (40.9 ng/ml; interquartile range (IQR) 8.9–197.6) than in wild-type cases (6.2 ng/ml; IQR 2.8–12.8; p = 0.003). Both percentage reduction in CEA levels (−10.7 vs. +13.4 %) and percentage of cases with CEA response (42 vs. 20 %) were significantly higher in mutated vs. wild-type/unknown patients (p = 0.007 and p = 0.027, respectively). In wild-type/unknown patients, CEA response was significantly correlated with DCR (p = 0.001) and resulted as a significant predictor of PFS both in univariate (p = 0.002) and in multivariate analyses (hazard ratio (HR) 0.27; 95 % confidence interval (CI) 0.11–0.66; p = 0.004); only a trend was found for OS prediction (p = 0.082). In EGFR-mutated group, CEA reduction did not show any correlation either with PFS or OS. CEA response after 1 month of EGFR-TKI therapy could be a useful marker, worthy to further studies, as early predictor of treatment outcome in EGFR wild-type/unknown unselected NSCLC cases for which no molecular predictor is yet available.