Numerical chromosomal changes in high-grade prostatic intraepithelial neoplasia (PIN) and concomitant invasive...

Prostatic intraepithelial neoplasia (PIN) is regarded as a precursor lesion of at least some prostatic cancers. Using interphase cytogenetics, an in situ hybridization technique with chromosome specific probes, we investigated 15 prostatectomy specimens containing both invasive carcinoma and PIN for the presence of numerical changes of chromosomes 7, 8, 10, 17 and X. The results were correlated with tumor stage and Gleason grade as well as with morphological features of PIN. Of the 15 carcinomas, four were disomic, five displayed at least focal chromosomal gains and six were found to be aneusomic. A non-disomic chromosomal status correlated well with a higher tumor stage and grade. Although the majority of PIN glands showed an eusomy, focal chromosomal gains within single glands or parts of a gland could be observed in 12 of the 15 cases. All but one specimen with non-disomic carcinomas also harboured areas of PIN with numerical chromosomal aberrations, often laying directly adjacent to tumorous glands. Additionally, focal non-disomies of PIN could also be detected in two cases with eusomic cancer. With regard to numerical changes in PIN and cancer, no significant preponderance could be observed for the five chromosomes tested. We conclude that numerical chromosomal aberrations are a frequent, but mostly focal event in PIN. This karyotypic instability is further evidence for the premalignant nature of this lesion.