Bcl-2 expression and oxidative stress markers in bladder cancer: a grade-dependent pattern with no direct association- a case-control study

To investigate Bcl-2 expression in bladder cancer tissues and evaluate serum oxidative stress markers MDA and CAT in relation to bladder cancer. Additionally, to determine whether Bcl-2 expression exhibits a grade-dependent pattern independent of oxidative stress. This case-control study included 140 patients with histologically confirmed bladder cancer and 50 age- and sex-matched healthy controls. Bcl-2 expression was assessed in tumor tissues using immunohistochemistry. Serum levels of MDA and CAT were measured spectrophotometrically in both groups. Compared to controls, bladder cancer patients had significantly elevated serum MDA levels and markedly lower CAT activity (p < 0.0001 for both). Bcl-2 positivity was detected in 8/140 (5.7%) tumors and showed a strong grade-dependent pattern (24.0% in low-grade vs. 1.7% in high-grade tumors, p = 0.0004). Additionally, Bcl-2 expression was significantly higher in non-muscle invasive bladder cancer (NMIBC) and early-stages disease. Bcl-2 expression in bladder cancer demonstrates a clear grade-dependent pattern, with higher positivity in low-grade tumors, independent of oxidative stress status. Although serum MDA and CAT levels differ significantly between patients and controls, they are not associated with Bcl-2 expression, suggesting distinct roles in bladder cancer pathogenesis.