Multitarget Fluorescence In Situ Hybridization Assay Detects Transitional Cell Carcinoma in the Majority of Patients with Bladder Cancer and Atypical or Negative Urine Cytology

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Abstract
The multitarget fluorescence in situ hybridization (FISH) probe set UroVysion (Vysis, Downers Grove, Illinois), containing probes to chromosomes 3, 7 and 17, and to the 9p21 band, has been recently shown to have high sensitivity and specificity for detecting transitional cell carcinoma. In this study we retrospectively tested 120 urine samples from patients with atypical, suspicious and negative cytology for whom concurrent and followup bladder biopsy data were available. We evaluated the ability of FISH to identify malignant cells in cytologically equivocal or negative cases. Archived slides from 120 voided (47) or instrumented (73) urine cytology specimens from patients with concurrent bladder biopsy and a minimum of 12 months of biopsy followup were subjected to hybridization with UroVysion. The cohort included patients with biopsy proven transitional cell carcinoma, which was grades 1 to 3 in 23, 35 and 24, respectively, and stages pTis in 3, pTa in 64, pT1 in 6, pT2 in 6 and pT4 in 3, while it showed negative histology in 38. Cytology findings were suspicious, atypical and negative for transitional cell carcinoma in 31, 49 and 40 cases, respectively. A positive FISH result was defined as 5 transitional cells or greater with a gain of 2 or more of chromosomes 3, 7 or 17, 12 cells or greater with 9p21 deletion, or 10% or greater of cells with isolated trisomy of 1 of chromosomes 3, 7 and 17. All except 12 of the 82 biopsy proven transitional cell carcinoma cases (11 pTa and 1 pT1 tumors) were positive by FISH (85% sensitivity). Sensitivity in patients with suspicious, atypical and negative cytology was 100%, 89% and 60%, respectively. Nine patients with atypical cytology had positive FISH in the setting of a negative concurrent bladder biopsy. However, 8 of these 9 patients (89%) had biopsy proven transitional cell carcinoma within 12 months following the date when the sample tested by FISH was obtained. The last of these patients with false-positive results had previously documented pTis disease, which was also present in the next bladder biopsy 15 months following the positive FISH result. The remaining 29 specimens from patients with negative biopsy and a negative 12-month followup tested negative by FISH (97% overall specificity). The UroVysion FISH assay provides high sensitivity and specificity to detect transitional cell carcinoma in cytologically equivocal and negative urine samples. These results emphasize the important role of this assay in the management of bladder cancer.