Faecal carcinoembryonic antigen (CEA) in patients with large bowel cancer

The possibility that faecal CEA may be a more useful measurement than serum CEA for the detection of large bowel cancer has received very little attention. For this reason faecal CEA was measured before and after tumour resection in colorectal cancer patients and in a variety of control subjects. CEA was extracted from faeces by a new method with 3M KCl and assayed by an EIA technique utilising two monoclonal antibodies. Mean +/- SE faecal CEA in 32 cancer patients was 4.15 +/- 1.17 micrograms/g preoperatively. Values were not related to either stage of disease or serum CEA and they fell to 0.83 +/- 0.34 micrograms/g (n = 20) following tumour resection (P less than 0.05). Mean +/- SE faecal CEA in 34 control patients with no known colorectal disease was 0.94 +/- 0.49 micrograms/g which was significantly lower than in the cancer patients (P less than 0.05). Furthermore faecal CEA in 25 patients with non malignant colorectal disease was 1.44 +/- 0.63 micrograms/g which again was significantly lower than that in the cancer patients. It is concluded that as CEA is present in the faeces of the majority of colorectal cancer patients even at early stages of the disease its measurement here may be more useful for the detection of large bowel cancer than that in serum.