Helminths in the induction of cancer II. Schistosoma haematobium and bladder cancer.

This article reviews the association between bilharziasis and bladder cancer. Cancer of the bladder is a well documented sequelae of chronic infection with Schistosoma haematobium. Bilharzial bladder cancer is a major cause of morbidity in many countries; it remains the most commonly diagnosed cancer of Egyptian men. Bilharzial tumors may be differentiated from non-bilharzial tumors by their younger age of onset, greater male/female ratio, pathology and clinical presentation. Bladder tumors have been successfully induced in animals exposed to S. haematobium cercariae. Dietary nitrosamines may exacerbate the induction of bladder cancer in the presence of S. haematobium. The exact mechanism of bilharzial bladder carcinogenesis remains unknown.