Objective:To investigate the influence of laparoscopic resection of colorectal cancer on postoperative micrometastasis of tumor cells. Methods:Using cytokeratin,CK20 mRNA as target gene,the RTPCR method was used to examine the preand postoperative changes in the number of tumor cells in the peripheral blood of 48 cases of colorectal cancer.Results:After operation, the number of tumor cells in peripheral blood was significantly higher in the laparoscopic surgery group as compared to that of traditional laparotomy operation group(P<0.05).The degree of increase in the number of tumor cells in peripheral blood after laparoscopic surgery was not related to patient′s age(P>0.05),but was significantly related to positive rate of proliferating cell nuclear antigen(PCNA)(P<0.05).Conclusions:Laparoscopic resection of colorectal cancer may increase the risk of hematogenous tumor metastasis,and this risk is ever higher in patients with PCNA≥50% who undergo laparoscopic resection of colorectal cancer.