Intriguingly, ypT3N0M0 rectal cancer patients with elevated pretreatment serum CEA levels may benefit from ACT (5-year CSS: 69.1 vs. 82.9%, P = 0.045) (Figure 3A), while ypT3N0M0 rectal cancer patients with normal pretreatment serum CEA levels did not benefit from ACT (5-year CSS: 89.3 vs. 89.3%, P = 0.885) (Figure 3B). This evidence concerns the gene CEACAM5 and rectal cancer.