The phenomenon of multifocality does not affect the biologic behavior of histologic prostate carcinoma

The affect of multifocality on the biologic behavior of histologic prostate carcinoma is a controversial issue. The aim of this study was to determine if tumor multifocality influences the prognosis of patients with prostatic cancer.

Samples consisted of 264 autopsy tissues from men older than 40 years of age and less than 98 years of age who died (between August 2002 and December 2005) of diseases other than clinically diagnosed prostate carcinoma. The entire prostate and seminal vesicles were sectioned, tinted, and fixed in acetic acid. Specimens were immersed in formalin, serial sectioned at a thickness of 4 mm, postfixed, resectioned at a thickness of 2 mm, dehydrated, cleared in xylene, and immersed in paraffin. Two expert pathologists examined the sections.

Most latent carcinomas (61%) were multifocal and were composed of 2 or more foci. Ninety percent of distinct foci were found to originate from the peripheral zone. Multifocality was more common among larger prostates, and large tumors were almost exclusively multifocal. Half of these had a total volume less than 1 cm3 and a Gleason score of 2 to 6; there was a clear correlation between tumor volume and Gleason score. Heterogeneity of Gleason grade in multifocal tumors was proportional to the number of foci. No statistically significant difference was observed with respect to capsular penetration or perineural or vascular invasion of multifocal tumors compared to those of unifocal tumors.

Despite relative heterogeneity, the biologic behavior of multifocal tumors is not different from that observed in unifocal histologic tumors.