Carcinoembryonic Antigen-related Tumor Kinetics After Eight Weeks of Chemotherapy is Independently Associated With Overall Survival in Patients With Metastatic Colorectal Cancer.

ABSTRACT

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 -0.5%/day are effective prognostic factors among patients with high serum CEA levels and could become useful intermediate endpoints of clinical trials.