[Value of fecal detection of cancer-associated antigens using monoclonal antibodies in the diagnosis of colorectal cancer].

Detection of cancer-associated antigens in feces by the method of binding inhibition ELISA using monoclonal antibodies were performed in sixty patients with colorectal cancer; seventy with non-malignant gastrointestinal diseases: and one hundred healthy individuals. Monoclonal antibodies used were: anti-colonic cancer CL-2, CL-3, and anti-pancreatic cancer PS-9, PS-10. The level of cancer-associated antigens detected in feces were significantly higher in patients with colorectal cancer than that of non-malignant GI diseases or healthy individuals. The positive rate of the antigens in colorectal cancer patients and normal individuals were: 61.1% vs. 7% as detected by CL-2; 53.4% vs. 9% by CL-3; 55% vs. 8% by PS-9; and 53.3% vs. 8% by PS-10. When a "cocktail" of CL-2, PS-9, and PS-10 was used, the positive rate was 92.5% in cancer patients, and 14% in control group. Cancer-associated antigens were found to be positive in all seven early staged (Duke's A) colorectal cancer patients. These results indicate the value of assaying cancer-associated antigen in feces as an aid to the diagnosis of colorectal cancer, especially in the early stage.