Comparison of carcinoembryonic antigen in tissue and serum with grade and stage of colon cancer.

Background: Serial plasma carcinoembryonic antigen (CEA) levels are routinely used to detect postoperative recurrence of colon cancers. However levels of intrinsic CEA production by individual tumors, which might be helpful for interpreting serum CEA levels, are not routinely available. Materials and Methods: CEA levels were determined in twenty tissue biopsy specimens of colon carcinoma and sixteen normal colonic tissue specimens from India, by immunohistochemistry (IH) and by quantitative enzyme immunoassay (EIA). Serum samples from 62 colon cancer patients and 25 healthy blood donors were analyzed for CEA by EIA. Results: Tissue CEA levels were highest for well differentiated adenocarcinomas (5.2-37 μg/g protein) with progressively lower levels seen in moderately differentiated and poorly differentiated tumors, and in normals. The intensity of immunostaining paralleled the levels determined quantitatively. Mean serum CEA levels were 1.5 ng/ml for normals and 4.2, 6.4, 23, and 102 ng/ml for Dukes'A, B, C and D stage tumors, respectively. Conclusion: Preoperative serum CEA levels do not, in themselves, take into account differences in CEA production between individual tumors. Determination of tumor CEA content by quantitative or immunohistochemical methods, could be a useful adjunct for the clinical management of colon carcinoma, by improving interpretation of serum CEA levels.