Immunohistochemical study of carcinoembryonic antigen, epithelial membrane antigen, and secretory immunoglobulin system in the large bowel adenoma-carcinoma sequence.

To identify parameters for the malignant potential of large bowel adenomas, we used the avidin-biotin-peroxidase complex (ABC) technique. Patterns of carcinoembryonic antigen, epithelial membrane antigen, IgAs, and secretory component in 31 tubular, tubulovillous, and villous adenomas with different grading of dysplasia (mild, moderate, severe) and with early cancer were studied. All markers showed different degrees of staining intensity and various cellular localizations. We found that these variations might be related to dysplasia grading. Adenoma size did not influence the marker patterns. IgAs seemed to be the more selective among the markers studied. Our results suggested a dysplasia-carcinoma sequence instead of an adenoma-carcinoma sequence concept.