Latent and clinically manifest prostatic carcinoma.

In a histological study of 17 prostates excised in toto for stages B and C primary carcinoma, we found one focus of well differentiated carcinoma in each of six prostates, which, in addition to these foci, had large tumors of invasive prostatic carcinoma. In four of the six prostates, the foci were located near but separate from the main tumor, and in the remaining two they were invaded by the main tumor. These findings strongly suggest that prostatic carcinoma is multifocal in origin and that focal well differentiated carcinomas are different in biological behavior from invasive poorly differentiated carcinomas.