Molecular forms of PSA

A new era of PSA testing has been ushered in by identifying and measuring various molecular forms of PSA in the serum. The introduction of these concepts into clinical medicine makes it possible for us to identify the carcinoma of the prostate at an early and curable state and to avoid negative and expensive biopsies of the prostate. The present state of data shows that percentage-free PSA and not percentage-bound PSA is the better discriminator within the total PSA range between 2.5-3.0 and 10.0 ng/ml to differentiate patients with an early-stage carcinoma of the prostate against those with benign prostate hypertrophy. In this range of data percentage-free PSA improved the clinical performance of the PSA test by 20-25%. If the total PSA value is normal (< 4.0 ng/ml), percentage-free PSA yields better sensitivity and, if the total PSA value is slightly elevated (4.1-10 ng/ml), percentage-free PSA improves specificity. Both aspects are highly desirable in View of the aim to detect an organ-located carcinoma of the prostate early and cost-effectively within a group of patients with a high prevalence of benign prostate hypertrophy (BPH).