EXPRESSION OF CARCINOEMBRYONIC ANTIGEN (CEA) AND NONSPECIFIC CROSS-REACTING ANTIGEN (NCA) IN GASTROINTESTINAL CANCER - THE CORRELATION WITHDEGREE OF DIFFERENTIATION

In spite of its reputation as a tumour marker, little is known about t he function of carcinoembryonic antigen (CEA). We examined the mRNA ex pression of CEA and NCA in 26 gastric and 14 colorectal cancers togeth er with adjacent morphologically normal mucosae. There was no signific ant difference between the CEA mRNA levels of colorectal cancer and ad jacent mucosa, whereas the CEA mRNA levels were significantly elevated in gastric cancer compared with normal gastric mucosa. The expression of NCA, on the other hand, was more cancer-specific and was significa ntly up-regulated in both gastric and colorectal cancers compared with the corresponding normal mucosae. No correlation was found between th e mRNA level and plasma CEA value. No significant up-regulation was re cognised in the node positive cancer, cancer with distant metastasis, or the metastatic tissues themselves. Marked diversity in the degree o f differentiation in gastric cancer tissues, however, resulted in vari ed expression of the CEA gene family, compared with the constantly hig h expression found in colorectal cancer. Further analysis revealed sig nificant up-regulation of NCA in well and moderately differentiated ga stric cancers over poorly differentiated cancers, suggesting that NCA might have roles in differentiation.