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

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.