Assessment of the Immunohistochemical Expression of Vitamin D Receptor, β-Catenin, and Ki-67 in Urothelial Carcinoma: A Cross-Sectional Study from Egypt

Abstract

Background: Conventional urothelial carcinoma (UC) requires accurate risk stratification, particularly differentiation between non-muscle-invasive (NMIBC) and muscle-invasive bladder cancer (MIBC) and between low- and high-grade tumors. This study evaluated immunohistochemical (IHC) expression of vitamin D receptor (VDR), β-catenin, and Ki-67 index in Egyptian patients with conventional UC. Methods: A cross-sectional study was conducted on 58 archived conventional UC cases diagnosed in 2023 at Al-Azhar University Hospitals. VDR positivity was defined as ≥10% cytoplasmic and/or nuclear tumor cell staining. Membranous β-catenin was considered preserved when >80% of tumor cell membranes were stained; otherwise, it was reduced. Nuclear β-catenin was considered positive when ≥5% of tumor nuclei were stained. Ki-67 was categorized as high using a ≥30% cutoff. Associations with grade, muscle invasion status, and lymphovascular invasion (LVI) were analyzed. Results: Mean age was 65.3 ± 9.3 years; 86.2% were males; 51.7% were MIBC. Compared with NMIBC, MIBC was significantly associated with high grade, non-papillary architecture, LVI, and high Ki-67. VDR positivity was detected in 82.7% of cases and showed no significant association with grade, muscle invasion, or LVI. Preserved membranous β-catenin was seen in 34.5% and was significantly associated with tumor grade but not with muscle invasion or LVI; nuclear β-catenin was absent. High Ki-67 (60.3%) was significantly associated with high grade and MIBC, with no association with age, sex, or LVI. Conclusions: In Egyptian conventional UC, Ki-67 was a significant marker for aggressive clinicopathologic features, while VDR lacked discriminatory associations and β-catenin findings were mainly grade-related.