Clinical evaluation of prostate biopsy parameters: gland volume and elevated prostate-specific antigen level.

PURPOSE: To determine whether excess prostate-specific antigen (PSA) improves the accuracy of predicting positive biopsy results. MATERIALS AND METHODS: Results of prostate biopsy in 130 consecutive patients were correlated with transrectal ultrasound (TRUS) findings, digital rectal examination results, serum PSA level, and excess PSA (serum PSA level minus predicted PSA level [prostate volume x 0.12]), alone and in combination. Random sextant biopsy was performed in all patients, as well as directed biopsy of any suspicious lesion seen at TRUS. RESULTS: Excess PSA alone was most accurate in the prediction of positive biopsy results. Use of an excess PSA of > or = 0 ng/mL instead of a serum PSA level of > 4 ng/mL to initiate prostate biopsy increased the positive yield from 49% to 56% and accuracy from 51% to 62%, eliminating 21% of biopsies while maintaining sensitivity at 94% (vs 95% with serum PSA level). CONCLUSION: Use of only excess PSA of > or = 0 ng/mL to initiate prostate biopsy results in the best combination of sensitivity and specificity compared with the other standard parameters.