Epidemiology of urothelial carcinoma.

The epithelium lining is defined as the mucosal surfaces of the renal collecting tubules, calyces and pelvis, as well as the ureter, bladder and urethra. The term "urothelium" is used to refer to these surfaces. Upper tract urothelial carcinoma is a rare subset of urothelial cancers with a poor prognosis. Urinary bladder cancer is the most common malignancy involving the urinary system. Upper tract urothelial carcinoma is more common in men than in women, with a male-to-female ratio of 2:1. The incidence of urinary bladder cancer is also higher in men. Cigarette smoking and occupational exposure are the main upper tract urothelial carcinoma and urinary bladder cancer risk factors, while other factors are more specific to the carcinogenesis of upper tract urothelial carcinoma (i.e. Balkan endemic nephropathy, Chinese herb nephropathy). In Egypt until recent years, urinary bladder cancer was the most frequently diagnosed cancer due to Schistosoma haematobium. Substantial knowledge exists regarding the causes of upper tract urothelial carcinoma and urinary bladder cancer, and epidemiological studies have identified various chemical carcinogens that are believed to be responsible for most cases of urothelial carcinoma. In the era of precision medicine, genetic effects might play a direct role in the initiation and progression of urothelial carcinoma.