Multivariate Cox analysis also revealed that ACT was not associated with improved CSS regardless of pretreatment serum CEA levels in ypTis-3N0M0 rectal cancer patients (elevated-CEA group: HR = 0.830, 95% CI = 0.484–1.422, P = 0.497; CEA normal group: HR = 0.966, 95% CI = 0.554–1.684, P = 0.904). The gene discussed is CEACAM5; the disease is rectal cancer.