Usefulness of the ratio free/total prostate-specific antigen in addition to total PSA levels in prostate cancer screening

Objectives, Two different studies were performed, The aim of the first study was to define whether the measurement of the ratio between free and total prostate-specific antigen (fit PSA) in serum may enhance the ability of PSA-based screening for early detection of prostate cancer in men with Elevated serum PSA levels. A second study was undertaken to investigate the value of fit PSA ratio in serum to improve the specificity of prostate cancer screening in men with serum SA levels between 2.5 and 10,0 ng/mL. Methods, In a retrospective study of 266 men with elevated PSA levels and proven biopsy results, fit PSA levels were measured using deep frozen serum samples. In a second study we enrolled 158 men with elevated PSA levels according to age reference ranges apparent from our current PSA screening study with additional measurement of the fit PSA rat io. All study volunteers with a free fit PSA ratio cutoff point of less than or equal to 22% underwent digital rectal examination, transrectal ultrasonography, and biopsy of the prostate. Free and total PSA levels were measured with the Delfia PSA dual label fit PSA kit (Wallac Oy Turku, Finland), Results. 106 of 158 men with elevated total PSA values between 2.5 and 10.0 ng/mL (group 1) have been further evaluated and 37 prostate cancers were detected. Mean percentage of free PSA was 10% in men with cancer and 22% in men with benign prostatic hyperplasia. Using a fit PSA ratio of less than or equal to 22% as a biopsy criterion 30% of the negative biopsies could be eliminated while still detecting 98% carcinomas. Conclusions. Measurement of fit PSA reduces the number of unnecessary biopsies in PSA screening without missing many cancers.