Chromosomal alterations detected by fluorescence in situ hybridization in urothelial carcinoma and rarer histologic variants of bladder cancer.

Fluorescence in situ hybridization (FISH) with the UroVysion probe set (Abbott Molecular, Des Plaines, IL) was used to assess 31 bladder cancers for chromosomal abnormalities, including 4 adenocarcinomas, 5 urachal adenocarcinomas, 6 small cell carcinomas, 7 squamous cell carcinomas, and 9 typical urothelial carcinomas. FISH was also used to assess the benign urothelium in 4 cases. There was a significant increase (P < .001) in the mean number of chromosome 3 (2.64 vs 1.51), chromosome 7 (2.61 vs 1.48), and chromosome 17 (2.41 vs 1.41) centromeric signals observed in cells from patients with cancer compared with patients without cancer. Of the 31 tumors, 29 (94%) demonstrated polysomic signal patterns in more than 10% of cells. In the 2 remaining tumor specimens, there was a high percentage of cells (>75%) demonstrating homozygous 9p21 deletion. The data from this study suggest that chromosomal abnormalities detectable by FISH in urothelial carcinoma are also common in rarer histologic variants of bladder cancer.