Cyclooxygenase-2 Expression in Urinary Bladder Transitional Cell Carcinoma and its Association with Clinicopathological Characteristics

Background: Transitional cell carcinoma (TCC) is the most predominant type of urinary bladder tumor. As cyclooxygenase (COX)-2 is recently introduced as an attractive target molecule in bladder TCC, we evaluated the immunohistochemical expression of this marker and its association with several clinicopathological characteristics. Materials and Methods: This cross-sectional study was performed in the Pathology department of Sina Hospital in Tehran, Iran during 2006-2011. Ninety-two paraffin embedded blocks were selected from patients with urinary bladder TCC who underwent cystectomy or transurethral resection (TUR). Then, we assessed COX-2 expression by immunohistochemical staining using antibody against COX-2. Staining in more than 5% of tumor cells was considered as positive expression. Results: COX-2 was expressed in 50 % of our patients. This marker was markedly expressed in high grade bladder TCC (62.1%) versus other grades and there was statistically a significant difference in COX-2 expression between various grades (p=0.008). In addition, patients' age, lymphatic and perineurial invasion were associated with the expression of COX-2 (p=0.001, 0.015 and 0.039, respectively). However, other parameters such as stage, tumor size, venous invasion and lymph node metastasis did not show any significant relationship with this marker (all, p>0.05). Conclusions: COX-2 was expressed in urinary bladder TCC especially in high grade forms, advocating its probable role in the differentiation of this tumor. Accordingly, COX-2 could be a valuable biological target molecule in the evaluation and treatment of patients with bladder TCC.