Factors involved in the high incidence of prostatic cancer among American blacks.

Microcarcinoma (incidental, latent) of the prostate gland occurred with a frequency of 11.7% and at an age-adjusted incidence rate (world standard) of 40.6% per 1000 necropsies in the sampled black male population. The frequency of microcarcinoma of the prostate in black males in Washington, D.C., is essentially the same as the frequency of latent carcinoma in other ethnic groups and in other geographic areas. Of the patients studied clinically, fifty-one percent (51%) were in low stage (Stages I and II) disease; sixty-three percent (62.7%) had a well differentiated, Grade I, carcinoma of the prostate; and forty-two percent (42.4%) were in the 65-74 age group. Mean plasma testosterone and estrone levels were significantly higher in cancer patients than in age-matched hospitalized controls. The factor with the highest risk ratio was urinary tract symptoms occurring 10 years or longer before the onset of the present complaints which led to the diagnosis or prostatic carcinoma. Although our studies did not directly implicate diet as a risk factor, published reports strongly suggest diet as a critical factor in the development of prostatic carcinoma.