Serum levels of tumor-associated glycoprotein (TAG-72) in digestive cancers

Serum levels of tumor-associated glycoprotein (TAG-72) were measured using a two-step sandwich radioimmunoassay kit in 281 patients with digestive cancers and 135 patients with benign digestive diseases. The positive rates of TAG-72 with the cut-off values of 2.2 and 4.0 U/ml were high in pancreatobiliary (56%, 38%), gastric (49%, 37%) and colorectal (62%, 29%) cancers, while the false-positive rate in benign diseases was 11%, 0.7% respectively. Very high levels were found in patients with advanced cancer. TAG-72 was positive in 17 (greater than 2.2 U/ml) and 7 (greater than 4.0 U/ml) out of 60 CEA-negative patients, and in 7 (greater than 2.2 U/ml) and 3 (greater than 4.0 U/ml) out of 17 CA19-9-negative patients. TAG-72 might be a useful serum marker for digestive cancers, especially gastric and colorectal cancers.