Background and study aims: Various methods of fluorescence excitation and detection have been developed in gastrointestinal endoscopy. This study reports an endoscopic technique using locally applied fluorescein-labeled antibodies for in-vivo detection of colorectal dysplasia and carcinoma.
Patients and methods: Fluorescence endoscopy with a fluorescein-labeled monoclonal antibody against carcinoembryonic antigen (CEA) was carried out in 27 patients with colonic polypoid lesions. During conventional colonoscopy, the monoclonal antibody was applied directly onto the mucosal surface. After an incubation time of 10 min, specific fluorescence was visualized with a conventional endoscope whose optical range was increased via two narrow-band filters.
Results: Fluorescence in vivo was present in 19 out of 25 carcinomas and in three of eight adenomas. The technique failed in the presence of mucosal ulceration or bleeding. One fluorescence-positive villous adenoma showed high-grade dysplasia, and another fluorescence-positive polypoid lesion was diagnosed as carcinoma in adenoma. Normal-appearing mucosa was fluorescence-negative in all cases. Endoscopic fluorescence significantly correlated with the CEA expression of luminal epithelial cells as determined immunohistochemically (Wilcoxon-Mann-Whitney U-test, P < 0.01). In all cases without ulceration or bleeding, the specificity of fluorescence endoscopy was 100%, the sensitivity was 78.6%, and the accuracy was 89.3%.
Conclusions: Fluorescence endoscopy using fluorescein-labeled monoclonal antibody against CEA was shown to be positive in most cancers and some adenomas. Further and larger studies will be needed to demonstrate the value of this technique for differential diagnosis.