Objective: To analyze the clinical value of reverse transcriptase-polymerase chain reaction (RT-PCR) recognition of mRNA coding for carcinoembryonic antigen (CEA) and cytokeratin 20 in blood obtained from patients with colorectal carcinoma.
Summary background data: RT-PCR has been applied to identify very small numbers of tumor cells. Molecular detection is thought to provide useful information for the clinical management of perioperative prophylaxis of tumor cell implantation or postoperative adjuvant therapy regimens.
Methods: From 52 patients with colorectal cancer, peripheral blood specimens were obtained before and after surgical manipulation; also, a specimen of mesenteric venous blood draining the colorectal tumor was obtained just before tumor resection. Using cDNA primers specific for CEA and cytokeratin 20, RT-PCR was performed to detect tumor cells. Subsequently, the 52 patients were divided into two groups, a group positive for both CEA and cytokeratin 20 and a group negative for CEA, cytokeratin 20, or both.
Results: On the basis of 450 days of follow-up data, the PCR-positive group had a significantly shorter overall survival than the PCR-negative group only with the mesenteric venous blood specimens. Multivariate analysis indicated that detection of the simultaneous presence of CEA and cytokeratin 20 mRNA in mesenteric venous blood is a potent prognostic factor independent of the traditional pathologic parameters. Of the eight peripheral blood specimens found to be PCR-positive, five showed a change of PCR from negative to positive during surgery, and liver metastases developed 11 months later in one of these five patients.
Conclusions: Molecular detection of both CEA and cytokeratin 20 mRNA in mesenteric venous blood may be of prognostic value for patients with colorectal carcinoma. Molecular detection in the peripheral blood at surgery suggests that hematogenic tumor cell dissemination is a common and early event and that surgical manipulation enhances this release of tumor cells into the circulation.