A Simple Immunohistochemical Panel Could Predict and Correlate to Clinicopathologic and Molecular Subgroups of Urinary Bladder Urothelial Carcinoma

Although gene expression profiling provided a comprehensive molecular characterization of different subtypes of bladder urothelial carcinoma (UC), which are distinct in their biological features and prognosis, such a system is not yet applicable for routine clinical practice. This study aimed to examine the expression of these molecular classes of UC using simple panel of immunohistochemical markers. Tissue sections from 192 specimens of UC were stained with FGFR3, CK5, CCNB1, HER-2, and P53. The molecular classes identified were correlated with clinicopathologic characteristics and patient survival. The most frequent class in our cohort was urobasal B (UroB) (44.1%), followed by squamous cell carcinoma-like (SCCL) (22%), genomically unstable (GU) (20.3%), and urobasal A (UroA) (13.6%). Patients with SCCL were significantly younger (P < .0001). Both the SCCL and GU types were of significantly higher histopathologic grade (P < .0001). UroA tumors were mainly of the T1 stage (75%), whereas 61.5% of the SCCL and 58.3% of the GU types were of stage T2 (P < .001). Prognosis was significantly different among groups. The SCCL class showed the lowest overall survival (38.5%; P = .030) and metastasis-free survival (69.2%; P = .017). The best prognosis was for UroA, with an overall survival of 75% and no metastatic events. The distribution of UC subtypes in our study was uniquely different from other studies. This simple immunohistochemical panel could be suggested as a clinically applicable tool that has the potential to be used routinely in guiding individualized treatment of UC. Bladder urothelial carcinoma subtypes identified with gene expression profiling need to be bridged over to routine clinical practice. A simple immunohistochemical panel of markers was applied to 192 specimens, and the 4 major subgroups were identified in 92.2% without overlap. The identified characteristics of urothelial carcinoma detected in our population can be used for individualized treatment planning.