DETECTION OF COLONIC CELLS IN PERIPHERAL-BLOOD OF COLORECTAL-CANCER PATIENTS BY MEANS OF REVERSE-TRANSCRIPTASE AND POLYMERASE-CHAIN-REACTION

Circulating tumour cells play a central role in the metastatic process , but little is known about the relationship between this cellular sub population and the development of secondary disease. This study was ai med at assessing the presence of colonic cells in peripheral blood of patients with colorectal cancer in different evolutionary stages, by m eans of reverse transcriptase polymerase chain reaction (RT-PCR) targe ted to carcinoembryonic antigen (CEA) mRNA. In vitro sensitivity was e stablished in a recovery experiment by preparing serial colorectal can cer cell dilutions. Thereafter, 95 colorectal cancer patients and a co ntrol group including healthy subjects (n = 11), patients with other g astrointestinal neoplasms (n = 11) or inflammatory bowel disease (n = 9) were analysed, Specific cDNA primers for CEA transcripts were used to apply RT-PCR to peripheral blood samples. Tumour cells were detecte d down to five cells per 10 mi blood, thus indicating a sensitivity li mit of approximately one tumour cell per 10(7) white blood cells. CEA mRNA expression was detected in 39 out of 95 colorectal cancer patient s (41.1%), there being a significant correlation with the presence of distant metastases at inclusion, None of the healthy volunteers and on ly 1 of 11 patients (9.1%) with other gastrointestinal neoplasms had d etectable CEA mRNA in peripheral blood, By contrast, CEA mRNA was dete cted in five of the nine patients (55.6%) with inflammatory bowel dise ase, These results confirm that it is feasible to amplify CEA mRNA in the peripheral blood, its presence being almost certainly derived from circulating malignant cells in colorectal cancer patients. However, C EA mRNA detectable in blood of patients with inflammatory bowel diseas e suggests the presence of circulating nonneoplastic colonic epithelia l cells.