Chromosomal high-polysomies predict tumour progression in T1 transitional cell carcinoma of the bladder

The main prognostic factor generally accepted for tumour progression in T1 transitional cell carcinoma (TCC) of the bladder is histological grade. Despite this fact it is considered inaccurate to make clinical decisions on individuals. It appears that progression from minimally invasive to deeply invasive cancer is concurrent with the acquisition of genomic alterations that increase the malignant potential of cancer cells. The aim of this study is to determine if changes in chromosomes 7, 8, 9 and 17 copy number can be used to predict recurrence and progression in patients with T1 TCC of the urinary bladder.

Thirty-one T1 TCC samples were analyzed for chromosomal alterations by fluorescence in situ hybridization using centromeric probes for chromosomes 7, 8, 9 and 17. Clinical data were collected from the patients' clinical records and correlated with chromosomal studies.

Histological grade was confirmed as a prognostic factor of tumour progression (p=0.01). None of the cytogenetic alterations demonstrated in the studied group could be related to tumour recurrence. The high-polysomies (five or more copies) of chromosomes 8, 9 and 17 showed predictive value (p=0.05, 0.05, 0.03 respectively) for tumour progression since it was observed that patients with high-polysomy of these chromosomes showed more risk of tumour progression towards muscle-invasive disease than those without high-polysomy alteration.

Our findings suggest a possible prognostic significance of highly aneuploid cells (high-polysomies of chromosomes 8, 9 and 17) in tumour progression of T1 TCC bladder tumours. FISH analysis is a reproducible technique for evaluating cytogenetic alterations and could contribute to the assessment of the individual prognosis of T1 transitional cell carcinoma of the bladder.