Free-to-total prostate-specific antigen (PSA) ratio contributes to an increased rate of prostate cancer detection in a Japanese population screened using a PSA level of 2.1–10.0 ng/ml as a criterion

Abstract

Although the free-to-total prostate-specific antigen (PSA) ratio (f/t ratio) is low in prostate cancer, its usefulness in mass screening remains unclear. We examined the clinical usefulness of the f/t ratio for screening in a Japanese population. Since 2000, we have performed PSA screening in Japanese men aged 55–69 years. From 2000 to 2002, patients with total PSA (tPSA) levels over 2.1 ng/ml were referred to the urological clinic for secondary screening, regardless of the f/t ratio. We analyzed both the tPSA level and the f/t ratio in prostate cancer patients, and since 2003, subjects with tPSA levels ranging from 2.1–10.0ng/ml and f/t ratios higher than 0.22 have not been referred for secondary screening. Here, we report the results of tPSA screening, comparing findings in the two periods (2000–2002 and 2003–2005). Between 2000 and 2005, we performed the tPSA screening test in 27 730 men, and detected 214 cases of prostate cancer. Sixty patients (28.0%) showed tPSA levels between 2.1 and 4.0ng/ml. There were no differences in cancer detection rates between the two periods in the populations referred for an initial screening. However, the percentage of individuals referred for secondary screening decreased from 17.0% to 13.0% during the later period (P < 0.001). The cancer detection rate in all patients with biopsies rose from 13.5% in the earlier period to 22.7% in the later period for the group with tPSA between 2.1 and 10.0ng/ml (P < 0.001). The f/t ratio may be a useful additional screening parameter for patients showing tPSA levels between 2.1 and 10.0ng/ml on their initial screening examination.