Prostate‐specific antigen corrected for prostate volume improves differentiation of benign prostatic hyperplasia and organ‐confined prostatic cancer

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Abstract
To determine whether the ratio of PSA and prostate volume provides additional useful information for the discrimination of benign prostatic hyperplasia from prostatic carcinoma. Since 1989, a prospective study has been in progress involving 229 patients (49 with locally confined prostatic carcinoma, 180 with benign prostatic hyperplasia) to establish whether the ratio of prostate-specific antigen (PSA) and prostate volume, determined by transrectal ultrasound (longitudinal x anterior-posterior x transverse diameter x 0.52), allows a better differentiation than the absolute PSA values. In this population of patients with prostatic disease, the positive predictive value for diagnosis of a prostatic carcinoma was 26% with an absolute PSA threshold value of 4.0 ng/ml, and 36% at a threshold value of 10 ng/ml. With a threshold value of the PSA/prostate volume ratio of 0.25 ng/(ml x cm3), the positive predictive value was 56% compared with 93% for a threshold value of 0.4 ng/(ml x cm3). The ratio PSA/prostate volume is a superior method for the diagnosis of prostatic carcinoma both with regard to its sensitivity and its specificity in patients with absolute PSA values in excess of 4 ng/ml.