P-GLYCOPROTEIN AS A PROGNOSTIC INDICATOR IN PRECHEMOTHERAPY AND POSTCHEMOTHERAPY OVARIAN ADENOCARCINOMA

P-glycoprotein (P-gp) is a plasma membrane efflux transporter that mai ntains the intracellular concentration of chemotherapeutic agents at l ow levels. Since the clinical outcome of ovarian adenocarcinoma depend s largely on its response to chemotherapy, an objective assessment of P-gp expression could serve as a prognostic indicator. Eighty-five pat ients were studied. Available tissue sections from the primary tumor ( n = 75) and persistent or recurrent lesions (n = 19) were tested with anti-P-gp (JSB-1) monoclonal IgG. Multivariate survival analysis using Cox regression was performed controlling for fixed covariates (age, s urgical stage, and presence of residual tumor) and included occurrence of postchemotherapy tumors and P-gp positivity in postchemotherapy ne oplasms as time-dependant variables. P-gp was expressed in 49 prechemo therapy (65.3%) and 14 postchemotherapy (73.7%) tumors. After controll ing for potentially confounding factors, patients with P-gp-positive p ostchemotherapy neoplasms were at three times greater risk of dying wi thin 2 years than their counterparts with P-gp-negative tumors (hazard ratio = 3.1; 95% confidence interval = 1.2, 9.1; p < 0.05). Detection of P-gp-expressive subclones can serve as an independent poor prognos tic indicator for patients with postchemotherapy tumors.