They also classified rectal cancer patients into 3 groups according to pre- and post-CRT CEA levels, though with different cut off values (> or ≦6 ng/ml), For patients with pre-CRT CEA >6 mg/ml, they were further divided by whether post-CRT CEA was ≥70% lower than pre-CRT CEA. This evidence concerns the gene CEACAM5 and rectal cancer.