CARCINOEMBRYONIC ANTIGEN IN HUMAN COLONIC ABERRANT CRYPT FOCI

Background/Aims: Aberrant crypt foci are putative preneoplastic lesion s that, by definition, are identified microscopically in whole-mount p reparations of colonic mucosa. Because the identification of hexosamin idase as a marker for rat aberrant crypt foci in histological sections facilitated their characterization, a similar marker for human foci i n histological sections was sought. Methods: Human aberrant crypt foci were marked in whole-mount preparations, embedded in paraffin, and ev aluated for their expression of carcinoembryonic antigen with two mono clonal antibodies. Results: Elevated expression of carcinoembryonic an tigen was detected in 39 of 42 (93%) aberrant crypt foci from 15 patie nts. The expression of carcinoembryonic antigen assisted in the evalua tion of longitudinal sections of foci, where dysplasia is more readily detected in these small lesions. The expression of carcinoembryonic a ntigen was related to the sizes of the foci (P = 0.0085, generalized F isher's Exact Test) but not to the presence or degree of dysplasia. Co nclusions: The overexpression of immunohistochemically demonstrable ca rcinoembryonic antigen is, to date, the only described alteration in m ost of these putative precursors of human colon cancer that differs fr om the expression in contiguous, normal crypts at the histological lev el and thus facilitates the identification of aberrant crypts in histo logical sections for further characterization.