The effect of radiation on prostatic growth.

Radiation is increasingly important in the treatment of prostatic carcinoma. The effect and mechanism of action of radiation on prostatic growth was studied using the ventral prostate of the testosterone-treated rat. Prostatic radiation blocked testosterone-stimulated prostatic growth. Electron microscopy showed this inhibition to be associated with specific morphologic alterations. While radiation caused profound inhibition of prostatic DNA synthesis, only modest effects on nuclear uptake of dihydrotestosterone and on prostatic 5alpha-reductase were observed. Based on these animal studies, it is concluded that a major mechanism whereby radiation blocks testosterone-stimulated prostatic growth operates through inhibition of DNA synthesis.