The pattern of
chromosomal aberrations and their significance in
prostate cancer are poorly understood. We studied 23
prostate cancer and 10
benign prostatic hyperplasia (BPH) specimens by fluorescence in situ hybridization (FISH) using pericentromeric repeat-specific probes for 10 different chromosomes. The aims of the study were: 1) to compare the sensitivity of FISH and
DNA flow cytometry in
aneuploidy detection, 2) to determine which chromosome copy number changes are most common, and 3) which probe combinations would be most effective in
aneuploidy diagnosis. Disaggregated
tumor cells from
formalin-fixed,
paraffin-embedded tissues were pretreated with our newly developed method based on hot
glycerol solution to improve probe penetration. All BPH specimens were diploid by
DNA flow cytometry and showed no numerical
chromosome aberrations by FISH. In
prostate cancer, flow cytometry showed abnormal
DNA content in 35% of cases, whereas 74% were abnormal by FISH. Aberrant copy number of chromosomes 8 (48% of cases), X (43% of cases), and 7 (39% of cases) were most common. Ninety-four percent of all
aneuploid cases would have been detected with these three probes alone. Simple chromosome losses were uncommon but in
DNA tetraploid tumors relative losses (
trisomy or disomy) of several chromosomes were often found, suggesting progression of
prostate cancer through tetraploidization followed by losses of selected chromosomes. In conclusion, our results indicate that FISH using three selected chromosome-specific probes is two to three times more sensitive than flow cytometric
DNA content analysis in
aneuploidy detection.