Cyclooxygenase-2 expression in invasive transitional cell carcinoma of the urinary bladder

Cyclooxygenase-2 (COX-2) activity is reported to increase apoptosis, inhibit angiogenesis and reduce metastasis. We analyzed COX-2 expression in patients with invasive bladder cancer to evaluate the feasibility of selective COX-2 inhibitor treatment targeting COX-2. Forty patients with pathologically diagnosed invasive transitional cell carcinoma of the urinary bladder (pT2-pT4) were evaluated. Immunohistochemical staining was used to evaluate COX-2 expression, and cases with staining of ≥10% of tumor cells were defined as positive. In 2 patients, 0% of the primary tumors stained for COX-2, while 1-5% was stained in 16 patients, 5-10% in 3 patients and ≥10% in 19 patients (19/40, 47.5%). In terms of grade, 2 patients with grade 2 (2/3, 66.6%) and 17 patients with grade 3 (17/37, 45.4%) were COX-2 positive. When categorized by stage, 11 patients with pT2 (11/22, 50.0%), 6 with pT3 (6/13, 46.1%) and 2 with pT4 (2/5, 40.0%) were positive. Lymph node metastasis was observed in 10 patients; 2 of them, with pN2, were COX-2 positive. Those with COX-2-positive metastatic lymph nodes had grade 3 primary tumors, which were also COX-2 positive. In addition, COX-2-negative metastatic lymph node patients also had negative primary tumors. The results of this study suggest that 47.5% of patients with invasive bladder cancer may benefit from treatment with selective COX-2 inhibitors targeting COX-2, and that treatment efficacy can be expected in patients with lymph node metastasis when their primary tumors are COX-2 positive.