Prognostic value of GST-pi expression in diffuse large B-cell lymphomas.

Abstract

Among mechanisms potentially involved in resistance to alkylating agents and anthracyclines, the glutathione system has been extensively studied in vitro. We analyzed by immunohistochemistry the relation between glutathione s-transferase pi (GST-pi) expression in tumor cells and outcome in 69 cases of diffuse large B-cell NHL (DLBCL). GST-pi expression was considered as low when <50% of tumor cells were stained and high when >/=50% tumor cells were stained. Median follow-up was 58 months. GST-pi expression was correlated with the probability of achieving complete remission (CR). Patients with high GST-pi expression had a worse 5-year freedom from progression (FFP). High GST-pi expression was associated with a trend for lower survival. In the group of patients with International Prognostic Index (IPI) 0-1, low GST-pi expression was associated with a CR rate of 88%, a 5-year FFP of 76+/-20% and a 5-year survival of 78+/-16% compared to 36, 14+/-16 and 40+/-32%, respectively, in patients with a high GST-pi expression (P=0.002, P&<10(-5) and P=0.01, respectively). No correlation was found between GST-pi expression and lactico deshydrogenase serum level, age, Ann Arbor stage, performance status, and IPI index. Both GST-pi expression and the IPI index correlated with FFP. After incorporating IPI and GST-pi expression in a multivariate analysis for FFP, GST-p expression remained the only prognostic factor (P=0.003). Our findings suggest that GST-pi expression had strong prognostic significance in DLBCL, which appears to be independent of other prognostic parameters in those disorders.