Effects of systematic 12-core biopsy on the performance of percent free prostate specific antigen for prostate cancer detection

Abstract

Purpose: The performance characteristics of percent free (f) prostate specific antigen (PSA) for differentiating between benign prostatic hyperplasia and prostate cancer were originally established using primarily sextant biopsy. We determined whether the addition of 6 laterally directed cores to the traditional sextant prostate biopsy affects the performance of percent fPSA.

Materials and methods: We retrospectively evaluated a cohort of 350 consecutive biopsies in men with negative digital rectal examinations and PSA between 4 and 10 ng/ml who underwent systematic 12 core biopsy (S12C) biopsy at Scott Department of Urology between March 1999 and January 2003. The effects of 6 additional, laterally directed biopsies on the sensitivity, specificity and area under the ROC curve for percent fPSA was evaluated in the 277 men in whom percent fPSA was measured.

Results: Cancers detected exclusively in the 6 laterally directed cores were associated with percent fPSA values similar to those in patients with a benign S12C biopsy. This resulted in a modest and yet predictable decrease in the sensitivity of percent fPSA at each biopsy threshold value without affecting specificity. There was a nonstatistically significant decrease in the area under the ROC curve with the addition of 6 laterally directed cores to sextant biopsy (medial sextant cores 0.66 vs S12C 0.60).

Conclusions: The 12 core biopsy strategies have a higher cancer detection rate than sextant biopsies and they are gaining widespread acceptance. The addition of 6 laterally directed cores to traditional sextant biopsy may result in a modest decrease in the sensitivity of percent fPSA at each selected biopsy threshold without affecting specificity.