Prognostic Significance of Bcl-2 Expression in Transitional Cell Carcinoma of the Bladder

Shin, Ki Yong; Kong, Gu; Moon, Hong Sang; Kim, Sun Jin; Lee, Tchun Yong; Lee, Jung Dal; Woo, Young Nam

Abstract

The protein encoded by the Bcl-2 proto-oncogene has been shown to prolong cell survival by preventing programmed cell death (apoptosis). Recent work has elucidated Bcl-2 expression in many solid tumors including bladder tumor. Because there exists some controversy as to the prognostic significance of Bcl-2 in bladder cancer, we examined the cellular expression of Bcl-2 protein using immunohistochemistry in tumor samples from 89 patients with bladder cancer and determined whether expression of Bcl-2 has prognostic significance in bladder cancer. We found Positive staining for Bcl-2 (>5% positive cells) in 41 patients (40%). Bcl-2 expression was strongly correlated with tumor stage and grade (superficial vs. invasive, p<0.025; grade II vs. grade III&IV, p<0.005). In superficial tumors, Bcl-2 expression was not correlated with disease- free survival (p>O.l) and weakly correlated with progression-free survival (p In invasive tumors, Bcl-2 expression was correlated with shortened actuarial survival (p<0.025). We assessed the effect of Bcl-2 status on the response to chemotherapy or radiotherapy in 25 patients with invasive tumor. The patients with Bcl-2 positive tumors had significantly higher response rate than with Bcl-2 negative tumors (p<0.05). These results suggest that Bcl-2 protein plays an important role in tumorigenesis of bladder cancer and that Bcl-2 expression is not superior to tumor stage and grade in assessing the prognosis of patients with superficial tumors. However, Bcl-2 expression is associated with shortened actuarial survival in the patients with invasive tumor, which may be partly due to chemosensitivity or radiosensitivity in relation to the apoptotic process.