CEACAM5 and colorectal cancer: Moreover, several authors propose tumor markers as prognostic factors in different tumors.1 In recent years, a multiplicity of tumor markers have been proposed for colorectal cancer (CRC).2–6 According to current guideline recommendations, carcinoembryonic antigen (CEA) is the most important tumor marker with regard to individual prognosis, detection of recurrent disease, and on-treatment monitoring in all stages of CRC.7–9