To investigate the chromosomal abnormalities present in bladder carcinoma using a fluorescence in situ hybridization assay and to correlate the genetic findings with the pathologic grade and stage.

Samples from 37 bladder carcinomas were obtained at cystectomy or transurethral resection. In all cases, a histologic evaluation and fluorescence in situ hybridization analysis were performed. Pericentromeric DNA probes for chromosomes 7, 8, 9, and 17, and locus-specific DNA-probes for the 9p21 and 9q34 bands, were used in the fluorescence in situ hybridization assay.

Grade 1-2 tumors were characterized by the loss of genetic material on chromosome 9 in 35.3% of cases and either no detectable alterations or multiple aneusomy events in 47.1% and 17.6% of the tumors, respectively. Polysomy was the most frequent occurrence in grade 3 and pT1-T4 carcinomas. No significant difference was found between the loss of 9p21, 9q34, or chromosome 9 and the different tumor classifications. A statistically significant difference was found in the frequency of polysomy between grade 1-2 and grade 3 tumors and between pTa and pT1-T4 tumors for chromosomes 7, 8, 9, and 17, as well as chromosome bands 9p21 and 9q34 (P <0.005).

These findings show that chromosome 9 losses do not correlate with the tumor grade or stage, but are the only aberrations found at a significant frequency in low-grade lesions. The results suggest that pT1 tumors are closely related to muscle-invasive tumors at the genetic level and show that polysomy of the chromosomes assessed correlates with high-grade and high-stage bladder carcinoma.