[The quotient of prostate-specific antigen and prostate volume. Improved differentiation between benign prostatic hyperplasia and locally circumscribed prostate cancer].

Absolute serum prostate-specific antigen (PSA) values are of little help in the identification of locally confined prostatic cancer (PCA), because of a considerable overlap with the PSA values found in benign prostatic hyperplasia (BPH). Prostate gland volumes were estimated sonographically in 112 patients using the product of the three maximal diameters (longitudinal, anterior-posterior, transverse) and the factor 0.52. PSA was determined with a monoclonal immunoenzymetric assay (Tandem-E, Hybritech). The prostates were removed by either transvesical prostatectomy (for BPH) or radical retropubic prostatovesiculectomy (for PCA). In each case the diagnosis was verified by systematic histological examination. The ratio of serum PSA to estimated prostate volume did not exceed 0.4 ng/(ml x ml) in any of the 74 patients with BPH, whereas 23 of the 38 patients with PCA had a ratio above 0.4 ng/(ml x ml). The information provided by the PSA-prostate volume ratio is superior to absolute PSA values in preoperative differentiation between BPH and PCA. With a PSA-prostate volume ratio over 0.4 ng/(ml x ml) patients are at high risk for PCA and should be evaluated by prostate biopsy.