Prostate specific antigen adjusted for the transition zone volume as an indicator of prostate cancer

We compared prostate specific antigen (PSA) adjusted for the transition zone volume with PSA and PSA density with regard to value in diagnosing prostate cancer in men with intermediate PSA levels of 4.1 to 10.0 ng./ml. in a community based urology practice.

Between October 1994 and May 1996, PSA transition zone was obtained from 92 of 94 men who underwent systematic sextant biopsies and had a PSA value between 4.1 and 10.0 ng./ml. PSA transition zone, calculated by dividing the PSA value by the volume of the transition zone of the prostate, was compared with PSA and PSA density via the receiver operating characteristic (ROC) curves.

Of the 92 men 12 (13.0%) had prostate cancer. ROC curve analysis demonstrated that PSA transition zone and PSA density predicted the biopsy outcome significantly better than PSA (p <0.05 and p <0.01, respectively). In a subset of 59 men with normal digital rectal examination PSA transition zone predicted the biopsy outcome better than PSA density, although without significant difference. With a cutoff value of 0.3 PSA transition zone had a sensitivity of 75% and a specificity of 54%.

PSA transition zone is more specific than PSA in distinguishing benign from malignant disease in men with intermediate PSA levels of 4.1 to 10.0 ng./ml., especially in those with normal digital rectal examination. Further study is necessary to discuss whether PSA transition zone is superior to PSA density.