[Levels of circulating tumor-associated glycoprotein (TAG-72) in patients with carcinoma using a novel tumor marker, CA 72-4].

CA72-4 is a novel quantitative immunoradiometric assay system utilizing two monoclonal antibodies CC-49 and B72.3, which recognize a tumor-associated glycoprotein (TAG-72). We have utilized the CA72-4 RIA kit to measure serum levels of TAG-72 in 205 patients with carcinoma and 192 patients without carcinoma. The cut-off value (4.0 U/ml) was obtained according to the levels and the distribution of CA72-4 in 468 healthy individuals. The positive rates in 82 patients with gastric cancer, 55 with colorectal cancer, 24 with pancreatico-choledochal cancer, 36 with breast cancer, and 3 with ovarian cancer were 52%, 55%, 46%, 39%, and 67%, respectively. Fifty percent of the sera from 205 patients with carcinoma demonstrated increased levels of CA72-4, whereas only 10% of the sera from 192 patients without evidence of malignancy showed levels more than 4.0 U/ml. The average level of serum CA72-4 in the patients with carcinoma was 38.6 U/ml, much higher than that (2.7 U/ml) in patients without malignancy. The patients with gastrointestinal cancer at advanced stages or at recurrence showed higher levels of serum CA72-4 than the patients with cancer at early stages. These results thus indicate that CA72-4 is clinically useful as a novel tumor marker, especially for monitoring serum levels of TAG-72 in patients with gastrointestinal cancer, breast cancer, ovarian cancer and other epithelial malignancies.