Postoperative methylated septin 9 in plasma may represent a potential noninvasive biomarker for CRC recurrence monitoring in addition to CRC diagnosis and prognosis compared with CEA and CA19-9.57 The circulating tumor DNA (ctDNA) minimal residual disease (MRD) following treatment in solid tumors predicts relapse and highlights the application of this potentially transformative biomarker.58 Here, CEACAM5 is linked to neoplasm.