In this analysis of a consecutive series of rectal cancer patients who underwent neoadjuvant chemoradiotherapy and radical resection from a single institution, the rate of postoperative pathologic complete response(pCR) was 20.8%, and we found that a pretreatment CEA level of ≤5 ng/mL and an interval from the completion of neoadjuvant chemoradiotherapy to surgery of ≥8 weeks were independent predictors of pCR. This evidence concerns the gene CEACAM5 and rectal cancer.