IMMUNOSCOPY - A TECHNIQUE COMBINING ENDOSCOPY AND IMMUNOFLUORESCENCE FOR DIAGNOSIS OF COLORECTAL-CARCINOMA

Background: Colorectal carcinoma is a common malignant disease with a high mortality rate. It arises most frequently in adenomas of the colo rectum with different grades of dysplasia. Endoscopy and biopsy are am ong the most reliable diagnostic tools currently available. Diagnosis of malignancy at an early stage is sometimes difficult. This study rep orts on a new method, ''immunoscopy'', that combines endoscopy and imm unofluorescent diagnostic procedures; it is the first reported use of locally applied fluorescein-labeled antibodies for detection of colore ctal carcinomas. Methods: A monoclonal antibody against carcinoembryon ic antigen was fluorescein labeled. In phase I, formalin-fixed tissue samples, and in phase II, postoperative fresh tissue samples from tumo rous and nontumorous areas of resected colorectal carcinomas were stud ied. After being incubated for 10 minutes, specific fluorescence was v isualized with a conventional endoscope whose range was increased by m eans of two narrow band filters. Results: Because of high levels of au tofluorescence, evaluation of immunoscopic investigations using formal in fixed tissue (phase I) was not carried out. Immunoscopic investigat ion with postoperative fresh tissue samples could differentiate betwee n tumorous and nontumorous areas (p < 0.001). Immunoscopic results wer e compared with data from immunohistochemical investigations with anti -carcinoembryonic antigen on the same tissue samples. Conclusions: Imm unoscopy can differentiate between malignant and benign mucosal areas in fresh tissue samples. The high sensitivity of immunoscopy could pot entially make it a useful diagnostic complement to routine endoscopy.