CEACAM5 and colorectal carcinoma: Although most studies assessed preoperative CEA levels (CEA-pre) or postoperative CEA levels (CEA-post) individually, (5–12) several systematic reviews on CEA levels’ ability to detect CRC recurrence argues that single CEA measurement is not a sufficient index, and the slope of the linear regression line of post-operational CEA showed better diagnostic performance (13, 14).