Qualitative and quantitative studies on detection of micrometastases in colorectal cancer

Abstract

This study aimed to investigate (a) the overexpression of carcinoembryonic antigen (CEA), cytokeratin 20 (CK20) and guanylyl cyclase c (GCC) in colorectal cancer (CRC), (b) the comparison between the results by qualitative and quantitative studies using conventional polymerase chain reaction (PCR) and real-time PCR (R-PCR) respectively, and (c) the effects of these analyses in the final re-staging of Dukesa?? B CRC. A total of 175 frozen lymph nodes (FT) and 158 formalin-fixed, paraffin-embedded lymph nodes (PET) from 28 CRC cases were studied. CEA, CK20 and GCC-specific qualitative conventional PCR and quantitative R-PCR were carried out on the mRNA transcripts, using the gel-based electrophoresis and LightCycleri?? (LC) technology respectively. Our results indicated a high incidence (>45%) of detecting micrometastases in histologically negative LN at the molecular level. There is discordance in the positivity of tumor markers in different tissue types (FT versus PET) and different methodology (gel-based qualitative studies versus LC-based quantitative studies). Multiple tumor markers are required to precisely predict the metastatic potential of Dukesa?? B CRC cases.