Glutathione S-transferase activity in human breast tumors

The level of total glutathione S-transferase (GST) activity was examined in forty-three breast carcinomas (forty tumors from previously untreated patients and three tumors from patients previously treated by chemotherapy), and thirteen benign breast tumors. Cytosolic GST activity was determined according to a spectrophotometric method. Using Student's t-test, significant differences were found between GST levels in these two groups of tumors (p < 0.01). The higher values were found in malignant tumors. The range of values in both malignant and benign tumors was very wide. The relationship between GST activity and hormone receptor status was examined in thirty-three cases for estrogen receptor (ER) status, and thirty-one cases for progesterone receptor (PR) status. The level of hormonal receptors was determined according to the dextran-charcoal technique. No significant difference between the mean levels of GST activity in ER+ and ER-tumors was found (p > 0.4), but the difference corresponding to PR+ and PR-tumors approximated the 1% level of significance. The relationship between total GST activity and clinical or pathological parameters was also studied. Significant difference was found between the mean levels of GST activity corresponding to the groups of patients with non-involved nodes, and those having one or more involved nodes, respectively (p < 0.05). No correlation was found with respect to age (p > 0.2), tumor size (p > 0.2), or tumor grade (p > 0.4). Increased levels of GST activity were found in PR-tumors and in tumors with involved axillary nodes. Both groups of tumors are known to have a poorer prognosis. It was concluded that the significance of GST activity as an additional marker of prognosis must be taken into consideration.