Lack of urothelial topical tumorigenicity and cotumorigenicity of schistosome ova in mice.

In certain endemic areas significant correlation exists between bladder cancer and Schistosoma haematobium infestation in rural males. The clinical presentation of bladder cancer asso ciated with chronic vesical schistosomiasis further supports the belief that neoplasia is a sequel to chronic inflammation with metaplasia. Ferguson (6), Makar (7), Aboul Xasr et al. (1), and Al-Waidh (2) have reported that unique clinical and histopathologic features characterize bladder cancer in areas where schisto somiasis is endemic. In these areas the high incidence of bladder cancer parallels the high incidence of schistosomiasis. A history of bilharzial cystitis frequently antedates the detection of bladder cancer. Aboul Xasr et al. (1) reported finding bilharzial cystitis in 97 % of 700 cases of bladder cancer in Egypt. The age distribution of bladder cancer in areas where bilharzial cystitis is prevalent favors a much younger population than that which obtains in nonendemic areas. Al-Waidh (2) found that the mean age of occurrence of bladder cancer in Iraq was in the 3rd decade. El-Mofty (4) reported that the mean age of occurrence in Egypt was 41.2 years. The histopathology of bladder cancer in areas of endemic bilharziasis differs from nonendemic locales. Squamous carcinoma constituted more than 50% of bladder cancers in endemic areas of bilharziasis (1, 2, 4, 8). Hypotheses on the etiologic role played by the parasite have been advanced. Fairley (5) reported development of adenopapillomas of the bladder in experimental bilharzial infestation in monkeys. These lesions were found mainly in S. haematobium infestations. They were interpreted to be the result of toxins liberated by the ova and the cellular infiltrate in the bladder wall. Shimkin et al. (9) were unable to demonstrate carcinogenicity of injected lyophilized material from Schistosoma monsoni worms and S. haematobium worms and ova.