Multivariate logistic regression model was adjusted for confounding factors including CEA, CA199, BMI, WBC, HB, PLT, ALB, Tumor Location (Upper, Middle, Low), Histological Subtype (Classic adenocarcinoma, Mucinous adenocarcinoma), Tumor Size and Bowel Obstruction (No, Yes).As showed in Tables 3 and 4, bowel obstruction were risk factors for over-T-staging in rectal cancer (OR = 3.120, 95%CI: 1.662–5.857, P < 0.001), while larger tumor size were protective factor for over-T-staging (OR = 0.837, 95%CI: 0.717–0.976, P = 0.024). This evidence concerns the gene CEACAM5 and mucinous adenocarcinoma.