Numeric alterations in chromosomes 7 and 8 detected by fluorescent in situ hybridization correlate with high-grade localized prostate cancer

Objective: To compare the ability of flow cytometry (FCM) and fluorescent in situ hybridization (FISH), using a small set of 4 enumeration chromosome probes to detect aneuploidy in prostate tumors, and to correlate it with histological grade and pathological stage. Methods: Among 28 suitable cases, 21 could be analyzed by FISH and FCM techniques. DNA centromeric probes were used in FISH analysis to enumerate chromosomes 7, 8, 10 and 12. Results: (a) Of the 21 cases studied by FISH, 5 were diploid, 14 aneuploid and 2 were tetraploid. When studied by FCM, these tumors were: 14 diploid, 6 aneuploid, and 1 tetraploid. FISH proved to have a higher ability for detecting DNA aneuploidy than FCM while been equally specific, since all tumors aneuploid by FCM were also found to be aneuploid by FISH. (b) Of the 14 aneuploid tumors, 12 were of high histological grade, while only 2 of the 7 nonaneuploid were of high grade. A statistically significant association was observed between high histological grade and FISH aneuploidy (p = 0.033). (c) All the aneuploid tumors showed chromosome 7 and/or 8 aneusomy. Trisomy 7 and monosomy 8 were the most frequent alterations present in 56 and 42% of the aneuploid tumors, respectively. Conclusion: FISH analysis of chromosome 7 and 8 alterations proved to be more sensitive than FCM in the detection of aneuploid prostate tumors. This aneuploidy was significantly associated with a poor pathological prognosis.