RESUMO
<p><b>OBJECTIVE</b>To inquire into the diagnostic significance of cytokeratin 19(CK19) and cytokeratin 20(CK20) expression on hematogenous micrometastasis of colorectal cancer.</p><p><b>METHODS</b>Forty-four patients with colorectal cancer were collected as colorectal cancer groups, and another 18 patients treated with abdominal surgical operations because of benign diseases were collected as benign disease group. Blood of all the patients was harvested from their portal and peripheral veins, and CK19 and CK20 levels in the blood were determined by RT-PCR.</p><p><b>RESULTS</b>There were no positive expression of CK19 and CK20 in the portal and peripheral blood of all the patients in benign disease group. Of the colorectal cancer group, 34 patients(77.3%) appeared positive expressions of CK19 and/or CK20 in portal and peripheral blood, and there was significant difference in the expressions of CK19 and CK20 between the two groups(P<0.05). Within the colorectal cancer group, the positive expression rates of CK19 and CK20 in peripheral blood were 36.4% and 52.3%, and the rates in portal blood were 59.1% and 72.7%. The rates of portal blood were significantly higher than those of peripheral blood(P<0.05). The positive expression rate in patients at stage III( was significantly higher than that in patients at stage I( orII( (P<0.05). The postoperative metastasis and recurrence rate of colorectal cancer in patients with positive expression of CK19 and CK20 in peripheral blood was 61.5%, which was significantly higher than that(25.0%) in patients with positive expression in portal blood only(P<0.05).</p><p><b>CONCLUSIONS</b>In patients with colorectal cancer, the expressions of CK19 and CK20, which are determined by RT-PCR in blood from portal and peripheral veins, are the sensitive and specific indexes for diagnosing hematogenous micrometastasis of the cancer.</p>