Glutathione S-Transferase π Immunostaining of Cisplatin-Resistant Ovarian Cancer Cells in Ascites

OBJECTIVE: To clarify immunohistochemically the correlation between glutathione S-transferase π (GSTπ) expression of surgically resected specimens and clinical response in ovarian cancer and to evaluate ascites cytology using GSTπ staining. STUDY DESIGN: Eighty-seven patients with ovarian cancer underwent initial debulking surgery and received cisplatin-based chemotherapy after surgery. Immunostaining for GSTπ was performed on formalin-fixed sec tions of the patients' tumors. The cytologic slides of 24 cases were acquired for evaluation of GSTπ staining. RESULTS: Of 87 surgically resected specimens, 55 (63.2%) were GSTπ positive. Twenty-five of 28 patients (89.3%) who showed no response to chemotherapy had GSTπ-positive tumor cells. The predictive value of positive GSTπ staining for drug resistance was 75.8% (25/33). Of 18 cases that were GSTπ positive in surgically resected specimens, 17 were positive In ascites cytology. Five cases were negative in both resected specimens and ascites cytology. There was a significant correlation in the GSTπlabelling index between resected specimen and ascites cytology from the same case; 1110 correlation coefficient was.701 and P value <.001. CONCLUSION: Overexpression of GSTπ is related to resistance to cisplatin, and GSTπ staining of ascites cytology can be used in pretherapeutic assessment of patients with ovarian cancer.