P-glycoprotein expression is a marker for chemotherapy resistance and prognosis in advanced ovarian cancer

Background: It was our aim to study the prevalence and possible prognostic and predictive significance of the expression of P-glycoprotein, a transmem brane transport protein related to classical multidrug resistance, in patie nts with advanced ovarian cancer. Study design: Tumor tissue from 73 previo usly untreated patients with FIGO stage 3 ovarian cancer was examined with immunohistochemistry for the expression of P-glycoprotein before and after chemotherapy. Response to 4 cycles of combination chemotherapy with cisplat in and epirubicin was assessed with second look laparotomy. The log lank te st was used for univariate survival and the Cox proportional hazards regres sion model for multivariate survival analysis. Results: P-glycoprotein expr ession was detected in 47% of untreated cases, and correlated with unfavour able prognostic factors such as advanced age, presence of ascites and large r residual disease deposits after primary surgery. P-glycoprotein negative cases responded significantly better to chemotherapy (P < .001). In the mul tivariate survival analysis P- glycoprotein expression was an independent p redictor of both overall (P = .045) and progression free (P = .006) surviva l When P-glycoprotein expression and residual disease status were considere d together, the patients could be divided in three clearly distinct prognos tic groups (P = .0009). Conclusion: P-glycoprotein expression is a predicto r of response and survival in a uniformly treated and followed cohort of ad vanced ovarian cancer patients.