Deletions of Chromosomes 9 and 8p in Histologically Normal Urothelium of Patients with Bladder Cancer

Specific genetic alterations frequently associated with bladder cancer are detectable in histologically normal urothelium of patients with bladder cancer, supporting the field effect hypothesis in urothelial carcinogenesis. However, intramucosal spread of tumor cells that escape light microscopic detection remains a possibility, since normal urothelium and concurrent carcinomas showed matching deletions. Chromosomal deletions in normal bladder mucosa are not a common finding and argue against a frequent genomic alteration of the entire urothelial field in bladder carcinogenesis.