CORRELATION BETWEEN TUMOR-ASSOCIATED GLYCOPROTEIN-72 MUCIN LEVELS IN TUMOR AND SERUM OF COLORECTAL PATIENTS AS MEASURED BY THE QUANTITATIVECA-72-4 IMMUNOASSAY

Colorectal tissue biopsies were obtained from 110 patients diagnosed w ith primary colorectal carcinoma (tumor and normal colonic mucosa samp les), 20 patients diagnosed with benign colorectal disease, and 31 hea lthy donors. The level of expression of tumor-associated glycoprotein 72 (TAG-72) was quantitatively measured in each sample using a double- determinant RIA with monoclonal antibodies B72.3 and CC49 and detectin g the sialyl-Tn epitope; this assay was termed CA 72-4. Statistical an alysis revealed a significant (approximately 10-fold) increase of TAG- 72 expression in the colon tumor biopsies when compared with the expre ssion in normal colonic mucosa from the same patients. A regression an alysis revealed a significant correlation (r = 0.459; P < 0.001) betwe en TAG-72 levels measured in biopsies from the tumor lesions and those found in the corresponding normal colonic mucosa. Furthermore, regres sion analysis showed a significant positive correlation between TAG-72 levels in the tumors and sera of the same patients (r = 0.491; P < 0. 001). TAG-72 levels in normal colonic mucosa from healthy donors and p atients diagnosed with colorectal cancer mere compared. TAG-72 express ion was 5-fold higher in the normal mucosa from the colorectal carcino ma patients. No relationship between TAG-72 tumor tissue content and s tage of disease was found. Moreover, the correlation between TAG-72 di stribution and degree of tumor differentiation observed (P < 0.05) was not any more evident when mucinous carcinomas were excluded. Finally, the results provide further evidence that TAG-72 may be considered an important early marker for colorectal cancer and/or other dysplastic colonic diseases. The statistical correlation between TAG-72 levels in tumors and circulating TAG-72 indicates that patients with elevated l evels of serum TAG-72, as measured by the CA 72-4 assay, would be most suited for diagnostic and/or therapeutic intervention with the anti-T AG-72 monoclonal antibodies B72.3 or CC49 or vaccine trials using the sialyl-Tn epitope.