Since the ultimate fate of the patients with colorectal cancer is related to three main factors (initial tumour stage, radicality of the surgical resection and effectiveness of adjuvant therapy – when necessary), the postoperative evaluation of the CEA level (after 5–6 weeks), in that it allows a reliable check of the last two factors, can be at least as important as the preoperative one. This evidence concerns the gene CEACAM5 and neoplasm.