Carcinoembryonic Antigen-Related Tumor Kinetics After Eight Weeks Of Chemotherapy Is Independently Associated With Overall Survival In Patients With Metastatic Colorectal Cancer

Although carcinoembryonic antigen (CEA) reduction is concomitant to the radiologic response and similarly is measured at CEA nadir, little is known about the early kinetics. In this retrospective analysis of 83 patients with high levels of baseline CEA who received a first-line chemotherapy, 2 CEA kinetics-related variables measured after 8 weeks predicted overall survival, and this relationship was more pronounced in right-sided tumors.Background: Carcinoembryonic antigen (CEA) best reduction after chemotherapy in patients with metastatic colorectal cancer (mCRC) has been reported as a prognostic factor. The study aims to evaluate whether serum CEA kinetics after 8 weeks of chemotherapy was prognostic in patients with mCRC. Patients and Methods: A retrospective analysis of patients with mCRC, who received chemotherapy and for whom CEA determinations were available at baseline and after 8 weeks, was performed. A Cox model was built including all variables with a significant correlation with overall survival (OS) after bivariate analysis. Results: Of 200 screened patients with mCRC, 83 were eligible and were enrolled for the analysis. Eighteen variables were tested in bivariate analysis with OS, and a Cox model was built up with 7 of them. Two of 5 CEA kinetics-related variables reported an independent effect on OS when included in the previous Cox model: the CEA response rate after 8 weeks (hazard ratio, 2.02; 95% confidence interval, 1.13-3.59) and the CEA-specific growth rate after 8 weeks (hazard ratio, 1.86; 95% confidence interval, 1.03-3.37). Conclusions: After 8 weeks from the beginning of chemotherapy, CEA reduction rate of 50% and CEA-specific growth lower than similar to 0.5%/day are effective prognostic factors among patients with high serum CEA levels and could become useful intermediate endpoints of clinical trials. (C) 2020 Elsevier Inc. All rights reserved.