ABSTRACT
There are few topics in clinical medicine that have been studied as extensively as the biochemistry and immunology of carcinoembryonic antigen (CEA). This substance was first described by Gold and Freedman in 1965 [1] in embryonic tissues and colonic adenocarcinoma. It was initially thought to be specific for the latter lesion and to reflect the neoplastic reactivation of a "repressed" gene family that was normally operative only during fetal life ; this belief led to the concept of "oncofetal" antigen expression in colonic cancer [1]. However, subsequent studies showed that a wide variety of extraintestinal tumors (and normal tissues) were also capable of expressing CEA or other molecular moieties that were closely related to it [2].
