Loss of Y chromosome in bilharzial bladder cancer

Bilharzial bladder cancer is the most common malignant neoplasm in Egypt, also occurring with a high incidence in other regions of the Middle East and East Africa. In a previous study, using centromere probes specific for chromosomes 3, 4, 7-11, 16, and 17, we demonstrated that monosomy of chromosome 9 (48.4%), and numerical aberrations of chromosome 17 (19.4%) were the most common observed imbalances. The present study extends the establishment of the baseline cytogenetic profile of this type of malignancy. Interphase cytogenetics by fluorescence in situ hybridization with the use of a panel of centromere-associated DNA probes for chromosomes 1, 2, 5, 6, 12, 13/21, 14, 15, 18, 19, 20, X, and Y was performed on paraffin-embedded bladder specimens from 25 Egyptian patients affected with bilharzial bladder cancer. No numerical aberrations were detected in the 25 cases for chromosomes 1, 2, 5, 6, 12, 13/21, 14, 15, 18, 19, 20, and X. However, loss of chromosome Y was observed in 7 of the 17 male cases studied (41.2%). No significant correlation was observed between loss of the Y chromosome and any of the different clinicopathologic characteristics of these cases. These data suggest that loss of the Y chromosome is the second frequent event that can occur in bilharzial bladder cancer. A molecular genetic model of bilharzial bladder cancer is evolving.