Bladder Cancer and Schistosomiasis: Is There a Difference for the Association?

Bladder cancer represents a significant worldwide health problem with an estimated 386,300 new cases and 150,200 deaths in 2008 worldwide. The majority of bladder cancer occurs in males and there is a 14-fold variation in incidence internationally. The highest incidence rates are found in the countries of Europe, North America, and Northern Africa (Jemal et al.2011). Smoking and occupational exposures are the major risk factors in Western countries, whereas chronic infection with Schistosoma hematobium (SH) in developing countries, particularly in Africa and the Middle East, accounts for about 50% of the total burden. The majority of bladder cancers associated with schistosomiasis are squamous cell carcinoma (Figure 1). Although the majority of bladder cancers, present with disease confined to the superficial layer of the bladder wall, approximately 20–40% of the patients will present with or subsequently develop invasive cancer. Bladder cancer is morphologically heterogeneous; more than 90 % of bladder cancer cases are urothelial (UC, transitional cell, TCC) carcinoma, whereas primary squamous cell carcinoma (SCC), adenocarcinoma, small cell carcinoma and other rare tumors are less common (Lopez-Beltran and Cheng, 2006). Urothelial cell carcinoma can present mixed with other malignant components (figure 2). These mixed forms of bladder histologies include squamous differentiation (present in 20 60% of bladder cancer cases), adenocarcinoma or glandular differentiation (10%), sarcomatoid (7%), micropapillary (3.7%) and lymphoepìtelioma-like carcinoma. About 1 in 25 Western men and 1 in 80 women will be diagnosed with bladder cancer (BC) sometime in their life. In many developing countries, life expectancy is much lower than Westerns, which is one of the reasons why overall BC incidence (not age-specific incidence) is lower in these developing countries (Albertson and Pinkel, 2003). It is associated with substantial morbidity and mortality. History of Tobacco smoking not only increases the incidence of BC, but also it can increase the tumor grade, its size and the number of tumor lesions (Muscheck et al, 2000). Chronic schistosomal cystitis was related for a long period to the development of BC in areas endemic for schistosomiasis like Egypt. In these areas, risk factors are many, including exposure to schistosomiasis, increased smoking rate and exposure to carcinogenic chemicals (Kallioniemi et al, 1992).