Relationship between Schistosomiasis and Bladder Cancer

Abstract

SUMMARY Carcinoma of the urinary bladder is the most common malignancy in the Middle East and parts of Africa where schistosomiasis is a widespread problem. Much evidence supports the association between schistosomiasis and bladder cancer: this includes the geographical correlation between the two conditions, the distinctive patterns of gender and age at diagnosis, the clinicopathological identity of schistosome-associated bladder cancer, and extensive evidence in experimentally infected animals. Multiple factors have been suggested as causative agents in schistosome-associated bladder carcinogenesis. Of these, N-nitroso compounds appear to be of particular importance since they were found at high levels in the urine of patients with schistosomiasis-associated bladder cancer. Various strains of bacteria that can mediate nitrosation reactions leading to the formation of N-nitrosamines have been identified in the urine of subjects with schistosomiasis at higher intensities of infection than in normal subjects. In experimental schistosomiasis, the activities of carcinogen-metabolizing enzymes are increased soon after infection but are reduced again during the later chronic stages of the disease. Not only could this prolong the period of exposure to activated N-nitrosamines, but also inflammatory cells, sitmulated as a result of the infection, may induce the endogenous synthesis of N-nitrosamines as well as generating oxygen radicals. Higher than normal levels of host cell DNA damage are therefore anticipated, and they have indeed been observed in the case of alkylation damage, together with an inefficiency in the capacity of relevant enzymes to repair this damaged DNA. In experimental schistosomiasis, it was also found that endogenous levels of host cell DNA damage were related to the intensity of infection. All of these factors could contribute to an increased risk of bladder cancer in patients with schistosomiasis, and in particular, the gene changes observed may have potential for use as biomarkers in the early detection of bladder cancer that may assist in alleviating the problem.

Genetic studies of African populations: an overview on disease susceptibility and response to vaccines and therapeutics

“…Another species, S. haematobium, causes the urinary form of the disease, associated with progressive granulomatosis of the bladder, resulting in obstructive uropathy (http://www.who.int/ schistosomiasis/en/). There is a signiWcant association between the urinary infection and squamous cell carcinoma of the bladder, and possibly of the liver infection with hepatocarcinoma, an enlightening example of pathogenetic link between infections and cancer in developing countries (Mostafa et al 1999). In 2000 it was estimated that approximately 200 million people were aVected in the developing world and nearly 85% (170 million) of these were in subSaharan Africa (Chitsulo et al 2000).…”

N-acetyl transferase-2 and bladder cancer risk: A meta-analysis

“…An increased risk is also seen in smokers, some two to six times greater than in nonsmokers [Brennan et al, 2000]. Other recognized risk factors include schistosomiasis infection [Mostafa et al, 1999] and exstrophy of the bladder [Mesrobian et al, 1988].…”

Imagerie des tumeurs urologiques dans une zone d’endémie bilharzienne au Mali

“…Certaines de ces atteintes ont été, d'un point de vue épidémiologique, trouvées associées à une tumeur maligne du tractus urinaire [5,7].…”

“…Le facteur prépondérant en Afrique sub-saharienne reste la bilharziose urinaire du fait de l'inflammation locale chronique quelle engendre au niveau de la vessie. En Égypte, les études ont montré que le cancer de la vessie est fortement lié à l'endémicité bilharzienne [4,7].…”