Significance of multi-drug-resistant proteins in predicting chemotherapy response and prognosis in epithelial ovarian cancer

Abstract

Objectives: To clarify the expression of multi-drug-resistant (MDR) markers, GST-pi, c-Jun, P-glycoprotein (Pgp), and MDR-associated protein (MRP) in epithelial ovarian cancer, and to determine whether their expression is predictive of chemotherapy response and patient prognosis.

Methods: Specimens of 58 epithelial ovarian cancer cases obtained at initial surgery were studied immunohistochemically using antibodies.

Results: Overall positive rates in the 58 specimens were 58.6% for GST-pi, 44.8% for c-Jun, 27.6% for Pgp, and 22.4% for MRP. The 5-year disease-free survival rate was 26.0% for patients with MRP-positive tumors and 75.2% for those with MRP-negative tumors. The prognosis for those with MRP-positive tumors was significantly poorer (p < 0.05). Patients with GST-pi-positive tumors had a significantly worse prognosis than those with GST-pi-negative tumors (51.9% vs 79.2%, p < 0.05). Multivariate analysis showed that residual tumors 2 cm or larger and MRP expression were independent prognostic factors for chemotherapy resistance. The relative risk of chemotherapy resistance in a patient with a residual tumor 2 cm or larger, positive MRP, and positive GST-pi was 10.6 times greater than the risk in a patient without these factors.

Conclusion: MRP and GST-pi expression might be potential predictors of the response to standard chemotherapy in epithelial ovarian cancer. Their expression also might contribute to individualizing clinical trials of postoperative chemotherapy.