Carcinoma of the prostate is the commonest malignancy in the male. However in the majority of cases it is discovered as an incidental finding either at postmortem or in surgical specimens removed for other reasons. In almost all instances the lesion is small, totally latent and without clinical significance. On the other hand, carcinoma of the prostate may behave as an aggressive spreading neoplasm that kills. Prostatic cancer, may therefore, exist in two biological forms: (1) a common small, incidental lesion and (2) a much less frequent, clinically significant disease that metastasizes and may cause death.