Background: The aim of the study was to evaluate the diagnostic efficiency of cathepsins B (cathepsin B and procathepsin B) in patients with transient cell carcinoma of the urinary bladder.
Methods: Serum and urine concentrations of cathepsin B and procathepsin B were measured by two commercially available enzymatic immunoassays in a group of 125 patients with bladder cell carcinoma without metastases and in a group of 72 healthy individuals. Concentrations in urine were adjusted to creatinine.
Results: Concentrations of both cathepsin B and procathepsin B in serum and urine were significantly elevated in patients with bladder cell carcinoma (p < 0.0001 for U-procathepsin B, U-procathepsin B/creatinine, and U-cathepsin B/creatinine, p = 0.0001 for U-cathepsin B, p = 0.0002 for S-procathepsin B and p = 0.02 for S-cathepsin B). Comparison of all diagnostic efficiencies of cathepsin B and procathepsin B in serum and in urine showed the best diagnostic accuracy for procathepsin B in urine (AUC = 0.81 vs. 0.50). The ratio of U-procathepsin B/creatinine was also more efficient than the ratio of U-cathepsin B/creatinine (AUC = 0.81 vs. AUC = 0.70). The diagnostic efficiencies of both parameters in serum were low (S-procathepsin B: AUC = 0.50, S-cathepsin B: AUC = 0.60). U-procathepsin B and U-procathepsin B/creatinine ratio show significantly better diagnostic efficiency in patients with invasive bladder tumors than other parameters (S-procathepsin B, S-cathepsin B, U-cathepsin B and U-Cathepsin B/creatinine; U-procathepsin B: AUC = 0.82, U-procathepsin B/creatinine: AUC = 0.86, S-procathepsin B and cathepsin B: AUC = 0.51 - 0.68).
Conclusions: Procathepsin B concentration in urine is a valuable diagnostic marker in patients with bladder cell carcinoma.