Abstract: ObjectiveTo evaluate the association between the decrease of the perioperative serum carcinoembryonic antigen (CEA) level during perioperative period and the prognosis in patients with colon cancer after a curative resection. MethodsRetrospective analysis was conducted to evaluate the relationship between preoperative serum CEA level and different clinicopathologic features in 605 cases who underwent a curative resection for colon cancer from January 2006 to April 2011. According to the preoperative serum CEA level, the patients were divided into two groups: ≤5 ng/ml and  >5 ng/ml group. The critical value of the CEA decreasing rate in preoperative serum CEA >5 ng/ml group was calculated, and the relationship between this critical value and survival rate was then analyzed. Univariate and multivariate models were used to detect the risk factors of overall survival rate (OS) and disease free survival (DFS) in preoperative serum CEA >5 ng/ml patients.  ResultsThe preoperative serum CEA levels were significantly associated with lymphatic invasion (χ2=14.122, P＜0.001), T stages (χ2=40.153, P<0.001), N stages (χ2=22.721, P<0.001) and pathological stages (χ2=38.576, P<0.001), except for sex (χ2=0.453, P=0.501), age (χ2=0.195, P=0.659) and histological stages (χ2=6.135, P=0.112). The critical values of CEA decreasing rate for OS and DFS were 48.95% and 50.81% in preoperative serum CEA >5 ng/ml group respectively. There were significant differences of 5year OS (31.37% vs. 76.63%, χ2=43.235， P＜0.001) and 5year DFS (27.69% vs. 72.10%, χ2=55.561，P＜0.001) between patients after operation whose CEA decreasing rate were lower than critical value and those whose were higher. Univariate analysis showed that the decreasing rate of CEA was an influence factor for OS (χ2=43.235， P＜0.001) and DFS (χ2=55.561， P＜0.001) of preoperative serum CEA >5 ng/ml patients. The N stages and pathological stages were both related to OS (χ2=14.683， P＜0.001； χ2=12.295， P<0.001) and DFS (χ2=16.212， P＜0.001； χ2=13.704， P<0.001) respectively. Multivariate model showed that the decreasing rate of CEA level and N stages were both associated with OS (χ2=18.885， P＜0.001； χ2=7.523， P＜0.001) and DFS (χ2=19.275， P＜0.001； χ2=6.997， P＜0.001) of preoperative serum CEA >5 ng/ml patients. ConclusionA high decreasing rate of serum CEA level after operation in colon cancer patients who have high CEA levels before the curative resection can be a protective factor for prognosis, especially when the decreasing rate is higher than the critical value.

Key words: Colonic neoplasms, Surgical procedures, operative, Perioperative period, Carcinoembryonic antigen, Prognosis