Y chromosome loss is a frequent early event in urothelial bladder cancer

Methods: A pre-existing bladder cancer tissue microarray (TMA) with clinical follow-up data including 516 urothelial bladder cancers from male patients was utilised in this study. Y chromosome losses were analysed by multicolour fluorescence in situ hybridisation (FISH) using a centromere Y probe and a centromere X probe. p53 immunostaining data were available for all patients from a previous study. Results: Y chromosome losses were seen in 23% of 477 interpretable cancers from male patients. There was no significant difference in patient age in tumours with (67.4 +/- 4.3 years) or without (67.3 +/- 2.3 years) Y chromosome losses (p = 0.9068). Y chromosome losses were equally frequent in tumours of all grades (p = 0.7831) and stages (p = 0.6140). There was also no association with p53 immunostaining (p = 0.4092). Y chromosome losses were not associated with survival in 224 invasive urothelial cancers (pT2-4; p = 0.2324), an increased risk for recurrences in 197 pTa tumours (p = 0.7649) or increased progression risk in 76 pT1 tumours (p = 0.4582). Conclusion: The data of this study show that Y chromosome losses are frequent in urothelial bladder cancer of all grades and stages, which could imply that loss of the Y chromosome is an early event in bladder cancer development. p53 mediated genomic instability is evidently not required for the development of Y chromosome losses. Since there was no correlation between Y chromosome losses and clinical outcome, detection of Y losses has no clinical relevance in urothelial bladder cancer.