Sex chromosome abnormalities in bladder cancer: Y polysomies are linked to PT1-grade III transitional cell carcinoma

Abstract

Background: Bladder cancer is a heterogeneous group of tumors from both the biological and clinical points of view. Conventional cytogenetics and molecular genetic techniques have shown non-random aberrations in bladder cancer, while certain chromosomal changes have been found to be highly correlated with tumor grade or stage. The aim of this study was to evaluate, by fluorescence in situ hybridization (FISH), the numerical aberrations of chromosomes X and Y in bladder cancer, comparing the incidence of nuclei with aneusomies in different grades or histological stages of the tumors.

Materials and methods: The FISH technique, using DNA probes specific for chromosomes X and Y, was applied to 35 male bladder tumor specimens directly processed for cytogenetic study.

Results: Polysomies of chromosome X were observed in 25 out of the 35 cases examined (71.43%), while numerical aberrations of chromosome Y were observed in 22 out of the 35 cases (62.86%). Of those cases with numerical aberrations of chromosome Y, 13 had polysomy (37.14%), while in 9 cases, loss of Y was observed (25.71%). Statistical analysis showed that numerical aberrations on chromosomes X or Y were not linked to histological stage, while a probable correlation was observed between aneusomies X or Y and tumor grade. Comparing the results of PT1-grade III tumors with those of PT1-grade II, statistical analysis showed that aneusomies Y and, especially, polysomy Y were correlated with PT1-grade III tumors, p = 0.023 and p = 0.010, respectively. An uncertain correlation between polysomy X and PT1-grade III tumors was found, p = 0.070.

Conclusion: Our results may suggest that the genetic instability associated with PT1-grade III tumors may account for the considerable potential for aggression of these tumors. However, to draw definite conclusions, a large number of cases must be studied.