Numerical chromosome aberrations in bladder cancer detected by in situ hybridization

To investigate the relationship between interphase cytogenetics and the grade and stage of bladder cancer in patients with transitional cell carcinomas of the urinary bladder.

By use of in situ hybridization with chromosome-specific DNA probes, the copy number of pericentromeric sequences on chromosomes 7, 10, 11, 17, 18, X and Y was detected within interphase nuclei in formalin-fixed and paraffin-embedded sections of the routinely processed bladder cancers from 20 patients. The percentage of hyperdiploid cells (three or more spots) was estimated using light microscopy.

The percentage of hyperdiploid cells for chromosomes 7, 11 and 17 was highly correlated with increasing tumour grade (P < 0.01, Spearman rank correlation) or increasing pathological stage (P < 0.01). The percentage of hyperdiploid cells for chromosome Y was not correlated with either grade or stage (P > 0.05). As high tumour grade and stage are both indicative of more aggressive tumour behaviour and a worse prognosis, these findings suggest that the percentage of hyperdiploid cells, especially for chromosomes 7, 11 and 17, may be highly predictive of bladder tumour aggressiveness.

These preliminary results suggest that measurement of numerical chromosome aberrations using in situ hybridization in bladder cancer may offer a new objective and quantitative assay of the biological potential of individual tumours.