Multidrug resistance gene-1 (Pgp) expression in epithelial ovarian malignancies.

To assess the value of P-glycoprotein (Pgp) expression in advanced epithelial ovarian cancer with regard to clinicopathological findings and disease prognosis. Twenty-four cases diagnosed as primary epithelial ovarian malignancies, between 1993-1999, were enrolled in this study. All of the cases had undergone cytoreductive surgery and an optimal staging procedure. Following cytoreductive surgery, in 18 patients, cisplatin+cyclophosphamide, and in six patients, cisplatin+paclitaxel combination chemotherapy regimens were initiated. After six courses of chemotherapy, cases were evaluated by pelvic examination, transvaginal ultrasound, pelvi-abdominal tomography and serum Ca-125 levels for the presence of residual disease. Following this evaluation residual tumor was detected in 14 cases and secondary cytoreductive surgery was undergone. In ten cases without any clinical and laboratory confirmation of the presence of tumor, second-look laparotomy was performed. In 24 epithelial ovarian cancer cases, both in primary or secondary cytoreductive surgery, Pgp expression was determined by immunohistochemical methods. Following primary surgery, in 25% (6/24) of cases, analysis of tumor specimens showed presence of Pgp expression. In cases recurring after first-line chemotherapy, Pgp expression was not statistically different in regard to chemotherapy regimen (p = 0.098). Pgp expression in tumoral tissues after chemotherapy did show a higher Pgp expression than before chemotherapy (p = 0.016). No significant correlation was relevant between Pgp expression and Ca-125 levels, histopathological differentiation, histologic subgroups of tumor, primary and residual tumor sizes and overall survival. In epithelial ovarian cancer, Pgp expression has no effect on overall disease survival.