Quantitative estimation of CEA and CK20 expression in tumour tissue of colorectal cancer and its liver metastases with reverse transcription and real-time PCR.

BACKGROUND Carcinoembryonic antigen (CEA) and cytokeratin 20 (CK20) are established tumour markers and the CEA pre-operative levels in serum have prognostic value. The aim of this study was to verify the usefulness of the estimation of CEA and CK20 gene expressions in tissues of colorectal cancers and their liver metastases. PATIENTS AND METHODS Two hundred and twenty-two specimens of colorectal cancers, their liver metastases, other liver tumours and control tissues were analysed by reverse transcription combined with real-time PCR. RESULTS The expressions of CEA and CK20 were significantly higher in tumours than in controls; there were differences between tumour types and no relationship to staging or clinical development was found. CK20 expression was inversely dependent on grading. The CEA expression in tumours did not correlate with the CEA levels in serum, but did correlate with serum tissue-specific polypeptide antigen (TPS). CONCLUSION The measurement of CEA and CK20 gene expressions in tumours did not supply any new prognostic information, but raised the question of the mechanism releasing CEA into the blood.