Glutathione S-transferase Pi expression in invasive breast cancer and its relation with the clinical outcome

Purpose: Glutathione S-transferase (GST) is a cytosolic enzymatic system involved in cellular detoxifying process. In vitro studies have shown that the presence of this enzymatic system in breast carcinoma cells can accelerate the elimination of drugs commonly used in chemotherapy, thereby decreasing its efficacy The aim of the present study was to evaluate the association between GST Pi expression by breast carcinoma cells and disease-free and overall survival. Methods: Ninety-five female patients with invasive breast carcinoma submitted to surgical treatment and adjuvant chemotherapy from January 1995 to June, 1997 and followed until August, 2006 were evaluated. The expression of GST Pi in breast carcinoma cells, determined by immunohistochemistry, was correlated with several clinical and pathological parameters of prognostic significance. Results: There were 36 (37.9%) GST Pi-positive cases. GST Pi immunoexpression was not significantly correlated with patient's age, histological tumor type, clinical stage, hormone receptor status and survival. On the other hand, GST Pi positivity showed a significant correlation with a lower histological grade/C-erb-B2 negative breast carcinoma phenotype. Conclusion: The findings suggest that GST Pi expression does not constitute a satisfactory prognostic factor in breast cancer.