Background: Urothelial carcinoma, previously known as transitional cell carcinoma, constitutes about 90% of bladder cancer cases and is highly prevalent in Iraq. It is linked to risk factors like tobacco smoking, chemical exposure, and schistosomiasis, and varies from low-grade tumors that rarely spread to aggressive high-grade forms that are prone to invasion and metastasis. FGFR3 mutations play a significant role in its pathogenesis, making FGFRs a potential target for cancer therapy. Aim of study: To evaluate the immunohistochemical expression of FGFR3 in urothelial carcinoma and correlate the expression with different cliniocopathological parameters. Materials and Methods: Sixty-three cases of Urothelial carcinoma of Urinary Bladder were included in this study. Immunohistochemical study for tissue sections were done to detect the reactivity of FGFR3 and correlate the results with different clinicopathological parameters. Results: FGFR3 expression in low grade tumors was positive in 76.1% of the cases whereas 47.1% of high grade cases were positive for FGFR3 (P<0.05). Immunohistochemical expression of FGFR3 in muscle invasive(T2) urothelial carcinoma was positive33.3%, non-invasive urothelial 81.08% (pta 89.5%, T1 72.2%) (P<0.05).
Conclusion:The expression of FGFR3 is observed in urothelial cancer. Our findings have demonstrated that low grade and low stage cancers have positive FGFR3 expression. supported statistically, FGFR3 protein expression has the potential to serve as an additional molecular marker, alongside tumor grading and staging, in the prediction of prognosis.