Numeric chromosome aberrations in prostate cancer detected by in situ hybridization

Background: This retrospective study was designed to examine the applicability of in situ hybridization to the study of numeric chromosome aberrations in conventionally fixed, embedded tissue sections of human prostate cancers. Methods: By use of in situ hybridization with chromosome- specific DNA probes, the copy number of pericentromeric sequences on chromosomes 7, 11, 17, X, and Y was detected within interphase nuclei in formalin-fixed and paraffin-embedded tissue specimens from 21 patients with adenocarcinoma of the prostate. The percentage of hyperdiploid cells (3 or more spots) was estimated by using light microscopy. Results: The percentage of hyperdiploid cells for chromosomes 7 and 17 was highly correlated with increasing tumor Mostofi grade (P< 0.05, Spearman rank correlation) or increasing Gleason score (P< 0.05). The percentage of hyperdiploid cells for chromosome 11 was not correlated with either tumor Mostofi grade or Gleason score (P> 0.05). Conclusion: Since high tumor grade is indicative of more aggressive tumor behavior and a worse prognosis, these findings suggest that the percentage of hyperdiploid cells may be highly predictive of prostate tumor aggressiveness. Our preliminary results suggest that measurement of numeric chromosome aberrations using in situ hybridization in prostate cancer may serve as a predictive factor for the prognosis of prostate cancer.