CEACAM5 and cancer: As per the up-to-date state of the art, cancer cell clonal monitoring within the tumor tissue under the selective pressure of the treatment is dictated by anatomic imaging, conducting scans every few months, or testing blood tumor-associated antigens (carcinoembryonic antigen (CEA), carbohydrate antigen 19-9 (Ca19.9), etc.)at the systemic level [11].