The demonstration of carcinoembryonic antigen in colorectal carcinoma and colonic polyps using an immunoperoxidase technique.

Carcinoembryonic antigen (CEA) has been demonstrated in tissues, by immunofluorescence, with conflicting results. Originally thought to be persent in colorectal carcinoma only, the antigen was later demonstrated in inflamed colonic mucosa and polyps. Using formalin-fixed, paraffin-embedded tissues and an immunoperoxidase technique, we have attempted to demonstrate CEA in 12 colorectal carcinomas, in adjacent benign mucosa, and in 42 polyps of varying histologic type. CEA was demonstrated in all colorectal cancers but not in adjacent inflamed mucosa. The antigen could not be demonstrated in polyps except in five cases where CEA was shown in morphologically atypical glands only. With out technique, the demonstration of CEA is a reliable indicator of malignant change in colonic mucosa. The findings in polyps tend to support the concept of carcinoma in situ in adenomatous polyps and the polyp-cancer sequence.