Glutathione S-transferase activity in patients with cancer of the digestive tract.

Glutathione S-transferase (GST) and carcinoembryonic antigen were measured in the plasma of 95 patients with neoplasm of digestive tract, in 40 patients suffering from non-neoplastic diseases and in 40 healthy subjects. The mean value of the GST activity was significantly (P < 0.001) elevated in patients with gastric, liver and colorectal cancer (10.4 U/l, 14.1 U/l and 12.3 U/l respectively) as compared with the reference population (3.2 U/l). GST elevations above normal were observed in 26 (90%) patients with gastric cancer, in 18 (100%) with liver cancer and in 25 (89%) with colorectal cancer. Carcinoembryonic antigen appeared less sensitive. In 15 patients the postoperative levels of serum GST were increased after surgery then gradually declined and after 1 month showed a normalization in 10 patients. Our data suggest that GST measurement may be useful as a tumour marker in gastric, liver and colorectal cancer. Moreover the combined determination of GST and other markers increase the sensitivity for cancer detection.