ESTRAMUSTINE POTENTIATES THE EFFECTS OF IRRADIATION ON THE DUNNING (R3327) RAT PROSTATIC ADENOCARCINOMA

The present study was designed to determine if estramustine phosphate (EMP) could potentiate the effects of irradiation on the Dunning (R332 7) prostatic adenocarcinoma in rats. Two groups of male Copenhagen x F isher F1 rats carrying bilateral tumors in the flank were used. Irradi ation was given with a linear accelerator 6 MV, in a dose of 6 Gy/day for 4 days to the tumor on one side while the tumor on the other side served as control. EMP (360 mu g/24 hours) was administered with osmot ic pumps to one group of rats for 2 weeks, starting 1 week before irra diation. Tumor growth was calculated by measuring tumor volume, and tu mor blood flow was measured 8 weeks after treatment. Irradiation alone effectively delayed tumor growth and EMP enhanced these effects. Tumo r blood flow was stimulated by EMP treatment irrespective of radiother apy. Volume density of tumor epithelium was effectively decreased by i rradiation but no significant effects could be seen after EMP. In conc lusion, the present study shows that EMP potentiates irradiation on ra t prostatic adenocarcinoma, and further evaluation of this therapeutic approach in the clinical treatment of prostatic carcinoma is thus jus tified. (C) 1994 Wiley-Liss, Inc.