High rate of expression of multidrug resistance-associated P-glycoprotein in human endometrial carcinoma and normal endometrial tissue.

The overexpression of P-glycoprotein was studied in 10 normal endometrial controls (five from the proliferative and five from the secretory phase of the menstrual cycle) and in 23 endometrial carcinomas of different histological varieties, using the C219 and JSB-1 monoclonal antibodies. Three of the tumours had been previously treated with combination chemotherapy containing doxorubicin. All endometrial carcinomas, whether treated or untreated, as well as the normal endometrial controls from both the proliferative and the secretory phase of the menstrual cycle, overexpressed P-glycoprotein. This puts endometrial carcinoma into the same category as other tumours arising in organs which normally overexpress P-glycoprotein, all of which tend to be intrinsically resistant to chemotherapy.