Radioimmunoassay for plasma glutathione S-transferase-pi and its clinical application in gastrointestinal cancer

Abstract

Background: Plasma acidic glutathione S-transferase (GST-pi) concentrations in 135 patients with gastrointestinal cancer were measured by an improved radioimmunoassay (RIA).

Methods: Blood was collected into a silicified glass tube containing a specific anticoagulant. The plasma, which was separated rapidly by centrifugation with adequate force, underwent RIA procedures (double antibody and polyethylene glycol separation method).

Results: The improved RIA for plasma GST-pi was specific and sensitive. Plasma GST-pi in 75% of patients with esophageal cancer, 64.44% of those with gastric cancer, 74.41% of those with colon cancer, 85.19% of those with hepatocellular carcinoma, and 60.00% of those with pancreatic cancer was elevated higher than 13.99 micrograms/l (mean + 1.96 standard deviation of normal controls). Plasma GST-pi levels in patients with gastric cancer with Stages I-II, III and IV disease increased in proper order. Plasma GST-pi concentrations in 57% of patients with colon cancer decreased to the normal range 14 days after surgery. Plasma GST-pi levels of patients with recurrent colon cancer were higher than of those with primary colon cancer.

Conclusion: The procedure for specimen collection must be critical. Plasma GST-pi may be useful in diagnosing gastrointestinal cancer and in monitoring its clinical course.