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Chromosomal aberrations in urothelial carcinoma of the bladder and the World Health Organization 2004 grading system.

OBJECTIVE
To evaluate differences in chromosomal aberrations in recurrent urothelial cancer (UC) of the bladder between the World Health Organization (WHO) 1973 and 2004 classification a retrospective study was performed.


STUDY DESIGN
Primary and recurrent UCs of the bladder of 22 patients diagnosed at the Institute of Pathology, Medical University of Innsbruck were analyzed by comparative genomic hybridization, fluorescence in situ hybridization and immunohistochemistry (Ki-67, p53).


RESULTS
On average, there were 5.8 +/- 5.9 alterations, including 4.1 +/- 4.3 gains and 3.5 +/- 2.5 losses per tumor. Most frequent gains ofchromosomal material were found on 19p, 7q, 16, 19q, 89, 12q and 20. Most frequent losses of chromosomal material were detected on 9, 13q, 5q, 8p, 11p and 18q. Total number of aberrations differed significantly between tumor grades of WHO 1973 and 2004 grading systems (p = 0.020 and p = 0.028). Chromosomal aberrations correlated well with both grading systems. Grade 2 tumors, reclassified as high-grade tumors, were of higher stage and showed aberrations usually associated with higher grade and poor outcome (1p+, 16p+, -2 and -5q).


CONCLUSION
Our findings suggest that G2 tumors form a heterogeneous group supporting the value of the new WHO 2004 classification.