Serum ribonuclease activity in the diagnosis of prostate cancer in men with serum prostate-specific antigen levels between 2.5 and 20 ng/mL.

Objectives: To evaluate the diagnostic value of serum ribonuclease activity for prostate cancer detection and to compare its performance with serum PSA.

Design And Methods: 111 subjects with serum PSA levels between 2.5 and 20 ng/mL underwent prostate biopsy. The diagnostic performance of serum ribonuclease activity, PSA, free PSA, complex PSA and PSA derivatives was studied in regard to discriminating prostate cancer from BPH.

Results: Of 111 patients, 27 (24.3%) were positive for prostate cancer. Median serum ribonuclease level in patients with prostate cancer was significantly higher than the non-cancer patients (21.3 U/mL vs. 6.6 U/mL, P < 0.001). Area under curve (AUC) values for ribonuclease activity level, PSA, f/tPSA and cPSA were 0.696, 0.514, 0.617 and 0.662, respectively. Of 27 patients with prostate cancer, radical prostatectomy was performed in 15. Of these 15 cases, four (26.7%) had clinical insignificant tumors; all with undetectable serum ribonuclease activity. When median values of various diagnostic parameters were compared in regard to predicting clinically significant and insignificant cancers, only serum ribonuclease activity was found to be significant.

Conclusions: Although serum ribonuclease activity had no additional benefit beyond serum PSA in the diagnosis of patients with PSA levels between 2.5 and 20 ng/mL, it may be helpful to discriminate the clinically significant prostate cancers and thus select the proper treatment accordingly.