Comparison of genetic changes in schistosome-related transitional and squamous bladder cancers using comparative genomic hybridization

The development of bladder tumors has been associated with a number of caus ative agents, including schistosomiasis. Schistosome-related cancers show d ifferent clinical and pathological features compared with non-schistosome-r elated bladder cancers, occurring in younger patients, and being predominan tly of squamous cell type. This study addresses the difference between squa mous and transitional tumor types in the presence of schistosome infection as a measure of the relationship between tumor genotype and phenotype, We h ave used comparative genomic hybridization to analyze primary muscle-invasi ve schistosome-related bladder tumors in 54 patients. Twenty-six of these t umors were squamous cell carcinomas; the remaining 28 were of transitional cell type. On average, transitional cell tumors showed 1.8 times the number of chromosomal aberrations as squamous cell tumors (14.4 versus 8.2, P < 0 .001). For both groups combined, the most prevalent genetic alterations wer e losses of 8p and 18q, and gains of 8q, Transitional cell cancers also sho wed frequent losses involving 5q, 9p, 10q, 11p and 11q, and gains at 1q and 17q. Loss of 11p was significantly more frequent in TCC than in SCC tumors (50 versus 4%, P = 0.01). Squamous cell cancers showed more frequent losse s of 17p and 18p than transitional tumors, which was clearly significant gi ven the overall reduced frequency of changes in squamous cancers (P = 0.001 and P = 0.03, respectively). These data show that different histologic sub groups of bladder tumors are characterized by distinct patterns of chromoso mal alterations. The genetic changes found in the transitional cell group a re similar to those reported in non-schistosome-related transitional cell t umors, but differ from tumors exhibiting squamous differentiation.