Immunohistological patterns of carcinoembryonic antigen in colorectal carcinoma. Correlation with staging and blood levels.

Forty-four primary adenocarcinomas of the large bowel and 2 liver metastases were stained for carcinoembryonic antigen (CEA) in tissue sections by indirect immunofluorescence. All tumours were positive and showed either one or more of 3 different patterns--luminal; linear at surface of the tumour cells; cytoplasmic. In most cases (83%), two or all 3 patterns were seen in the same or in different parts of a tumour. The immunohistological staining was concordant with preoperative blood levels of CEA in 31 cases (67%) in that 26 tumours showed strong immunofluorescence associated with blood CEA above 2.5 micrograms/l, and 5 showed weak staining and blood CEA values less than 2.5 micrograms/l. However, in 7 strong staining was associated with low blood CEA, and in 8 weak staining was associated with high blood levels. The dissociation between histological and blood CEA findings in 1/3 of the cases, together with the marked variation within the same tumour and differences between one of the primaries and its liver recurrence, suggest that CEA immunohistology is of no better prognostic value than blood CEA levels. There was no association between CEA immunohistology and tumour staging or differentiation. However, blood CEA levels were significantly higher in tumours with extensive local or distant spread (stage D) and in poorly differentiated tumours.