Tumour cell dissemination following endoscopic stent insertion

Background: This study examined whether colonoscopy or endoscopic stent insertion increases levels of carcinoembryonic antigen (CEA) and/or cytokeratin (CK) 20 mRNA expression in the peripheral circulation of patients with colorectal cancer. Methods: Peripheral venous blood samples were obtained before and after colonoscopy (38 patients) or colonic stent insertion (20). Twenty patients undergoing colonoscopy for benign conditions served as controls. Expression of mRNA was quantified using real-time reverse transcriptase-polymerase chain reaction. Results: Circulating CK20 mRNA was detected in 13 of 38 patients who had a colonoscopy and eight of 20 patients with stent insertion. CK20 mRNA expression was increased following stent insertion (P = 0.007) but not after staging colonoscopy (P = 0.454). CEA mRNA was detected in one patient who had colonoscopy and two who had a stent inserted. Neither CEA nor CK20 mRNA was found in blood samples from controls. Conclusion: Endoscopic insertion of colonic stents but not staging colonoscopy results in increased levels of CK20 mRNA in the peripheral circulation.