Comparison of fluorescence in situ hybridization and flow cytometric DNA ploidy analysis in paraffin-embedded prostatic adenocarcinoma specimens.

Cancer cell nuclei extracted from 15 paraffin-embedded radical prostatectomy specimens were examined with fluorescent in situ hybridization (FISH) and flow cytometry (FCM) for DNA ploidy. Repetitive chromosome-specific alpha-satellite DNA probes to centromeres 7 and 10 were used in the FISH assay. Results from FISH and FCM were compared and viewed in relation to clinical experience. Of the 15 tumors examined, 9 were hyperdiploid for at least one chromosome by FISH assay. Seven were aneuploid by FCM, showing a good correlation between the two methods (P = .006). Using either evidence of clinical progression or a postoperative prostate-specific antigen (PSA) level > 0.5 ng/mL by Hybritech assay to indicate the risk of clinical progression, 56% of FISH hyperdiploid tumors had a risk of progression of carcinoma versus 17% of FISH diploid tumors. A preoperative PSA level > 30 ng/mL had a marginal correlation with risk of progression (P = .05). We demonstrate that FISH is a useful tool for chromosomal analysis in paraffin-embedded tumor specimens.