Immunostaining of colorectal cancer with monoclonal anti-CEA antibodies compared to serum and tumor CEA content.

Carcinoembryonic antigen was measured in serum and in extracts from 37 colorectal tumors and we found a poor correlation between circulating and tumor CEA. Monoclonal antiCEA antibodies were used in indirect immunoperoxidase staining of the corresponding formalin fixed tissue sections. We found that serum CEA measurement had a sensitivity of only 41.9% as compared to 90.3% for the immunohistochemical staining. The positive and negative predictive values for immunostaining were respectively 96.6% and 72.7%. Immunohistochemical staining of tissue sections with monoclonal anti CEA coupled to other biochemical or immunological assays could be a useful adjunct for the diagnosis of premalignant or slightly modified tissues.