Tumor-associated antigens in polyps and carcinoma of the human large bowel.

The presence of a number of tumor-associated antigens was studied in eight metaplastic polyps, 22 tubulovillous adenomas, and 20 carcinomas. Specific tumor antigens were identified using the immunohistochemical (P.A.P.) technique to detect carcinoembryonic antigen (CEA), human placental lactogen (HPL), alphafetoprotein (AFP), colon-specific antigen (CSA), pregnancy-specific beta lipoprotein 1 (SP1), human beta chorionic gonadotropin (beta hCG), and placental alkaline phosphatase (P Alk P), isoferritins (FE), and transferrin (TF). There is no difference in either the number of antigens present or the number of cases positive for each antigen in cancers and tubulovillous adenomas, but the majority of metaplastic polyps show only CEA and HPL positivity. The two metaplastic polyps showing a full range of positivity were atypical and over 5 mm in diameter. The findings have shown a remarkable similarity between polyps and cancer, which strengthens the concept of the relationship between adenomatous polyps and carcinoma of the colon.