Interphase cytogenetics of prostatic adenocarcinoma and precursor lesions: analysis of 25 radical prostatectomies and 17 adjacent prostatic intraepithelial neoplasias.

Twenty-five radical prostatectomy specimens were screened for the presence of numerical chromosome changes within the adenocarcinoma as well as 17 adjacent prostatic intraepithelial neoplasias (PIN) by means of interphase in situ hybridization (ISH) to routinely processed tissue sections. To this end a defined alfoid repetitive DNA probe set was used, specific for the centromeres of chromosomes 1, 7, 8, 10, 15, and Y. The cytogenetic information was correlated with histopathological and clinical features as well as with DNA ploidy. Numerical aberrations of at least one chromosome were shown in 13 of 25 cases (52%). Alterations of chromosome 8 and loss of the Y chromosome were the most frequent findings (both 20%), followed by loss of chromosomes 15 (16%) and 10 (12%). Gain of chromosome 7 was seen in 8% of cases. No aberrations of chromosomes 7, 8, 10, and 15 were found in the adjacent PIN lesions, whereas loss of the Y chromosome in both PIN and tumor occurred in two cases. Also, (low level) aneuploidy was observed in 76% of these PIN lesions. Ploidy of the carcinomas as assessed by ISH correlated well with ploidy measured by DNA flow cytometry (FCM; P < 0.02). Due to the more specific correspondence between ISH and tumor pathology, pathologic grade correlated with ISH aneuploidy (P < 0.05), whereas FCM ploidy did not. Furthermore, genetic heterogeneity within a tumor was seen, as judged by the focal appearance of chromosomal aberrations. Chromosomal alterations occurred in all grades and stages, although loss of chromosome 10, gain of chromosome 7, and aberrations of chromosome 8 tended to predominate in more advanced cancers.