Expression of CK20 and telomerase in colorectal carcinoma micrometastasis and its significance WANG Tao*, YANG Xiong Fei, ZHANG Wei-sheng , et al. *Lanzhou University, Lanzhou 730000 ，China Corresponding author:Wang Tao ,E-mail：wangtaolanda@yahoo.com.cn Abstract Objective To investigate the detection of sentinel lymph node micrometastasis(SLNMM) and its clinical significance in these patients. Methods In a prospective study,122 SLNs were searched and examined successfully in 61 among 64 cases of DukesB colorectal carcinoma,using the immunohistochemical(IHC) staining to detect cytokeratin20(CK20) and telomerase in proper order,while the SLNs were negative by routine hematoxylin and eosin(HE) staining.Following up at least 3 years,memorized these patients’ clinical pathological parameters and survival numerical data, and analysis the dependablity. Results 9 SLNs of 6 cases were postive by HE staining;27.3%(15/55) in cases,which were negative by HE staining, were CK20 postive expression by IHC; Micrometastasis was also detected in12cases(21.8%,12/55) byIHC anti-telomerase staining.Combining the two methods can improve the micrometastasis rate as 38.2%(21/55) (P<0.05);The percent of carcinoma recurrence or metastasis for the DukesB patients with SLNMM(+) was significantly higher than that for the patients with SLNMM(-)(P<0.05),but the survival percent for the patients with SLNMM(+) was significantly lower than that for the patients with SLNMM(-).However,compared with 45 DukesC patients,the percents were no significant difference.In contrary,the percents of recurrence or metastasis and survival between DukesC patients and SLNMM(-)DukesB patients were significantly different(P<0.05).Conclusion Combining examination of immunohistochemical anti-CK20 and anti-telometase staining can improve the detection rate of SLNMM in DukesB colonrectal carcinoma patients, and it is of important clinical significance for staging Dukes, selection of adjuvant treatment and evaluation of prognosis in patients with colcrectal carcinoma.