IMMUNOCYTOCHEMICAL DETECTION OF P-GLYCOPROTEIN - INITIAL EXPRESSION CORRELATES WITH SURVIVAL IN RENAL-CELL CARCINOMA PATIENTS

We evaluated 28 patients with advanced renal cell carcinoma for the in itial expression of P-glycoprotein (MDR1 gene product) employing immun ocytochemistry. Tumor specimens were obtained upon primary tumor nephr ectomy. In all patients, progression-free survival time following neph rectomy was evaluated and correlated statistically with the staining r esults. Progression-free survival of patients with no or very few (< 1 %) P-glycoprotein-positive tumor cells (n = 8, median survival 27.0 mo nths) was significantly extended (p < 0.04) as compared to patients wi th 1% or more P-glycoprotein-positive tumor cells (n = 20, median surv ival 4.0 months). Correlations with histopathological tumor characteri stics were insignificant. These results suggest a potential role for P -glycoprotein as a biologic parameter predictive of tumor progression in renal cell carcinoma patients.