TAG-72 (CA 72-4 ASSAY) AS A COMPLEMENTARY SERUM TUMOR-ANTIGEN TO CARCINOEMBRYONIC ANTIGEN IN MONITORING PATIENTS WITH COLORECTAL-CANCER

Background. Serum carcinoembryonic antigen (CEA) is the most frequentl y chosen tumor marker in the clinical diagnosis of colorectal carcinom a and in the long-term monitoring of patients after tumor resection. I n recent years, monoclonal antibody technology has identified several new markers of neoplasia, two of which, TAG-72 and CA 19-9, are found in the sera of patients with adenocarcinoma. Serum CEA, TAG-72, and CA 19-9 were evaluated in 300 patients with either malignant (n = 200) o r benign (n = 100) colorectal disease. Methods. Serum CEA, TAG-72 (CA 72-4), and CA 19-9 antigen levels were determined with a double-determ inant radioimmunometric assay kit. Samples and appropriate standards w ere assayed in duplicate. The cutoff limits used for each assay were i ndicated by the manufacturer. All of the results of the CA 72-4, CEA, and CA 19-9 serum assays were separated from the clinical information until the study was completed. Results. Of the 200 patients with color ectal carcinoma, the percentage of patients whose serum samples were p ositive for CEA, TAG-72, or CA 19-9 was 43%, 43%, and 27%, respectivel y. The measurement of TAG-72 with CEA for patients with primary or rec urrent colorectal carcinoma increased substantially (to 60%) the perce ntage of positive serum samples when compared with measuring each seru m tumor marker alone. Moreover, the apparent advantage gained by measu ring the two tumor markers was achieved with little increase in the nu mber of false-positive results. Conclusions. The findings support prev ious observations of complementary expression of TAG-72 and CEA and in dicate that a significant advantage could be gained in the detection o f primary and, perhaps, recurrent colorectal carcinoma by incorporatin g the measurement of serum TAG-72 with that of CEA.