Role of adrenal androgens in prostate regression in rats treated with an antiandrogen and an LHRH agonist

Effect of early exposure of flutamide on subsequent growth of transplantable rat prostatic tumor (dunning R-3327)

Rat transplantable prostatic tumors (Dunning R-3327) were treated with flutamide before tumors grew palpable, in order to examine the effect of short term treatment of antiandrogen for prostatic cancer in latent period on the growth after appearance of tumor. Flutamide delayed an appearance of the tumor nodule and retarded the growth rate in proportion as treatment began earlier. Flutamide also reduced final tumor volume. Flutamide-treated tumors histologically consisted of small or dilated glandular structure with an increase in stromal area, but androgen receptors were preserved. Flutamide-treated tumor showed slow growth with androgen sensitivity when transplanted to intact rats, showing prolonged influences of antiandrogen on tumor growth. There was no significant difference between flutamide-treated and control groups in weight of accessory sex organs and serum androgen or estrogen levels. In conclusion, flutamide treatment may retard an appearance of prostatic cancer concomitant in benign prostatic hyperplasia.