Most investigators have accepted the association between schistosomiasis and bladder cancer since the work of Ferguson in 1911. Bladder cancer is the fourth most common cancer in men and the eighth most common in women, accounting for 8% of adult cancers. It is estimated that 54,300 new cases and 12,400 deaths were reported in the USA in 2001. Cell cycle proteins are important markers in predicting tumor behavior in urothelial carcinoma of the bladder. Over- expression of the D1 cyclins allows uncontrolled tumour cell proliferation. This study was designed to investigate the immunohistochemical expression of cyclin D1 in the two commonest types of bladder cancer in relation to tumor grade, to evaluate their role on the tumorgenesis and progression of bladder cancer (associated with bilharziasis or not associated). Our results showed it is generally over-expressed in urothelial carcinoma compared to non-malignant lesions and to squamous cell carcinoma. It's down regulation was associated with aggressive bladder cancers. In conclusion, Cyclin D1 expression is not just a research tool. In bladder cancers, cyclin D1 expression may provide prognostic information important in the management of patients with these diseases. In the future, the cyclin D1 gene and/or protein may be a site for immunotherapy. Before such treatments are possible, the full significance of this molecule in different variants of bladder cancer needs to be examined.
