['There is strong epidemiological evidence that prostate disease is significantly less prevalent in the Orient, where the intake of soy products is very high, than in the United States. We therefore undertook a study of the effects of genistein, a major component of soy, on growth of human-patient benign prostatic hypertrophy (BPH) and prostate cancer tissue in three-dimensional collagen gel-supported histoculture.', 'Surgical specimens of human BPH and cancer were histocultured for 5 days to study the effects of genistein on growth, as measured by inhibition of 3H-thymidine incorporation per microgram protein on day 5.', 'Genistein in doses of 1.25-10 micrograms/ml decreased the growth of BPH tissue in histoculture in a dose-dependent manner, with little additional effect at higher doses. Prostate cancer tissue in histoculture was similarly inhibited by these doses of genistein.'] Does genistein inhibit the growth of human-patient BPH and prostate cancer in histoculture?