NUMERICAL CHROMOSOME-ABERRATIONS IN BLADDER-CANCER DETECTED BY IN-SITU HYBRIDIZATION

Objective To investigate the relationship between interphase cytogenet ics and the grade and stage of bladder cancer in patients with transit ional cell carcinomas of the urinary bladder. Patients and methods 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 a nd paraffin-embedded sections of the routinely processed bladder cance rs from 20 patients. The percentage of hyperdiploid cells (three or mo re spots) was estimated using light microscopy. Results The percentage of hyperdiploid cells for chromosomes 7, 11 and 17 was highly correla ted with increasing tumour grade (P < 0.01, Spearman rank correlation) or increasing pathological stage (P < 0.01). The percentage of hyperd iploid cells for chromosome Y was not correlated with either grade or stage (P > 0.05). As high tumour grade and stage are both indicative o f more aggressive tumour behaviour and a worse prognosis, these findin gs suggest that the percentage of hyperdiploid cells, especially for c hromosomes 7, 11 and 17, may be highly predictive of bladder tumour ag gressiveness. Conclusion These preliminary results suggest that measur ement 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.