The Association of Serum Carcinoembryonic Antigen, Carbohydrate Antigen 19-9, Thymidine Kinase, and Tissue Polypeptide Specific Antigen with Outcomes of Patients with Metastatic Colorectal Cancer Treated with Bevacizumab: a Retrospective Study.

The aim of our retrospective study was to analyze the association of selected tumor markers (TMs) including serum carcinoembryonic antigen (CEA), carbohydrate antigen 19-9 (CA 19-9), thymidine kinase, and tissue polypeptide specific antigen with outcomes in patients with metastatic colorectal cancer (mCRC) treated with bevacizumab. There is an increasing body of evidence from retrospective/observational studies that some serum TMs may be predictive of effect of targeted therapies in mCRC. In our study, the cohort included 152 patients treated with bevacizumab-based therapy between years 2005 and 2014 at Department of Oncology and Radiotherapy, Medical School and Teaching Hospital Pilsen. Serum samples for measurement of TMs were collected within 1 month before the initiation of bevacizumab-based treatment. In multivariate Cox analysis that included serum tumor markers and clinical baseline parameters, the number of metastatic sites (hazard ratio [HR] = 2.00, p = 0.001) and CEA levels (HR = 2.80, p < 0.001) were significantly associated with progression-free survival, whereas CA 19-9 levels (HR = 2.25, p = 0.008) were the only studied parameter associated with overall survival. Quantification of serum CEA and CA 19-9 is simple and readily available, and their candidate prognostic importance in the setting of antiangiogenesis therapy deserves to be studied in prospective trials.