Diagnostic significance of gastric cancer associated antigens (MG-AGS) in serum, ascitic fluid and gastric juice.

A group of monoclonal antibodies against gastric cancer, pooled in equal proportions, was used to investigate their corresponding antigens (MG-Ags) in serum and body fluid of patients with gastrointestinal cancer and benign diseases using microsphere-ELISA method. The mean serum level (plus 3 standard deviations) in 59 normal subjects was arbitrarily set as the positive threshold value. The positive rate was found to be 68.8% (135/196) in sera of patients with gastric cancer, 70% (14/20) in colonic cancer, 72.2% (24/33) in rectal cancer, 43.8% (7/16) in esophageal cancer, 45.5% (5/11) in cholecystic cancer and 34.9% (15/43) in lung cancer, which, however, was not found in primary liver cancer, pancreatic cancer and ovarian cancer. In 214 patients with benign diseases, a false positive rate was 7.48%. In gastric juice and ascitic fluid of patients with gastric cancer, the positive rates were found to be 61.7% (27/44) and 83.3% (20/24) respectively. These antigens were also determined repeatedly in sera of patients with gastric cancer who had undergone gastrectomy. It was found that the level of MG-Ags in sera began to decrease at 8-10 days after operation. These results suggest that the determination of MG-Ags is useful in the diagnosis of gastrointestinal cancer and evaluation of the treatments.