Evaluation of prostate cancer risk in men with PSA < 1.5.

Abstract

64 Background: Prostate Specific Antigen (PSA) screening remains controversial primarily because of over detection and treatment. There is an unmet clinical need to identify patients at increased risk for high-grade (HG – Gleason Score ≥7) prostate cancer (PCa) since PSA has low sensitivity. Combining PSA with well-validated prostate cancer biomarkers (PCM) can improve risk assessment. We investigated the performance of three PCMs (phi – prostate health index, 4KScore, and SelectMDx) on patients with PSA levels < 1.5 ng/mL that represent a “safe zone” where risk of any PCa is rare Methods: 652 men were screened for PCa during the annual Prostate Cancer Awareness Week at the University of Colorado Hospital. This study was supported by Prostate Condition Education Council and the Schramm Foundation. phi is evaluated using p2PSA, total PSA, and free PSA in serum. Phi < 52.7 suggests absence of HG PCa. 4KScore incorporates four kallikrein protein biomarkers: total PSA, free PSA, intact PSA, human kallikrein protein, and clinical information. A 4KScore < 20% suggests absence of HG PCa. The SelectMDx post-DRE urine test measures mRNA levels of the homeobox C6 and distal-less homeobox 1 biomarkers. SelectMDx score of 0% indicates absence of HG PCa. Results: No patients with a PSA < 1.5 had SelectMDx > 0% and/or phi > 52.7. One patient had a 4KScore of 27%, indicating a risk for HG PCa. For patients with PSA between 1.5-3.99, 2.9% (4/135), 7.4% (4/54), and 2.3% (2/85) had positive phi, 4KScore, and SelectMDx results, respectively. Conclusions: Men with PSA <1.5 ng/mL are at very low risk for HG PCa. Men with PSA between 1.5-3.99 with positive PCM results may be referred for further evaluation. [Table: see text]