Clinical relevance of the individual prostate cancer focus

The course of stage A prostate cancer is difficult to predict because some of the tumors sampled at TURP are histologically "latent" (resembling cancer discovered incidentally at autopsy) and others have the ability to progress clinically. TURP selectively samples cancer in the transition zone, but, as we noted, the pattern of cancer in the TURP was a limited predictor of residual cancer. Furthermore, peripheral zone cancer appeared histologically to have a higher grade, volume for volume, than transition zone cancer and, in our study, was more frequently associated with extraprostatic spread of cancer. Peripheral zone cancer, while sampled in a minority of TURPs (less than 20%), is associated with histological predictors of poor prognosis. In the ploidy study, peripheral zone cancer was sampled in 5 patients, 4 of whom had nondiploid residual cancer in the radical prostatectomy specimen. Three of these 5 had extracapsular extension and 2 had seminal vesicle invasion. The frequent pattern in stage A1 is, therefore, a low-volume, diploid, transition zone cancer in the TURP specimen. In most cases this was associated with one or more small diploid transition zone or peripheral zone cancers in the radical prostatectomy specimen. However, in some cases, a residual nondiploid cancer was present that could eventually cause progression. The pattern of cancer in stage A2 differs from that in stage A1 in that most large transition zone cancers are selected into this stage and some of these are nondiploid. Stage A2, therefore, includes the minority of transition zone cancers that are nondiploid as well as a considerable number of peripheral zone cancers that are nondiploid. In both stages A1 and A2 nondiploid peripheral zone cancers outnumbered nondiploid transition zone cancers. The relationship of tumor volume with ploidy is clearly different for peripheral zone and transition zone cancers. Eight peripheral zone cancers less than 2.0 cc were nondiploid but only 1 transition zone cancer less than 2.0 cc was nondiploid. Furthermore, all peripheral zone cancers greater than 2.0 cc were nondiploid whereas only 50% of transition zone cancers greater than 2.0 cc were nondiploid. There was a significant difference between tumor volume of diploid and nondiploid cancers. Presumably, nondiploid cell lines have a growth advantage and are more poorly differentiated than diploid cancers. Whether DNA ploidy changes occur as a consequence of tumor growth and tumor cell heterogeneity is unclear because of range in volume of tumors studied.(ABSTRACT TRUNCATED AT 400 WORDS)