Assessment of high-grade prostate cancer risk using prostate cancer biomarkers

INTRODUCTION

To identify patients at risk of high-grade prostate cancer using prostate cancer biomarkers.

MATERIALS AND METHODS

A total of 601 men were screened for prostate cancer in 2012, 2015, and 2016 using prostate cancer biomarkers: prostate health index (phi), 4KScore, and SelectMDx. The first two are blood tests that incorporate several PSA isoforms; SelectMDx measures mRNA levels of homeobox C6 and distal-less homeobox 1 in post-digital rectal examination urine samples. The performance of each biomarker was evaluated using cut off values based on published literature. Gleason Grade Group (GG) ≥ 2 is considered as high-grade prostate cancer.

RESULTS

For patients with PSA < 1.5 ng/mL, none were at risk for GG ≥ 2 cancer based on SelectMDx > 0%, whereas 17.1% were at intermediate to high risk of finding GG ≥ 2 cancer with 4KScore ≥ 7.5%, and 3.5% were at risk of finding any prostate cancer with phi ≥ 36 at biopsy. For cut offs revised for finding men at high risk for GG ≥ 2 cancer at biopsy, only one patient with PSA < 1.5 ng/mL would be at risk with 4KScore ≥ 20% and none with phi ≥ 52.7. For patients with PSA 1.5 to 3.99 ng/mL, 2%, 8%, and 1% were at high risk for finding GG ≥ 2 cancer at biopsy based on phi, 4KScore, and SelectMDx, respectively.

CONCLUSIONS

Men with PSA < 1.5 ng/mL are at very low risk of finding high-grade prostate cancer at biopsy. However, some men with PSA between 1.5 to 3.99 ng/mL may be at intermediate to high risk for high-grade prostate cancer. Thus, primary care physicians could run biomarkers test and refer those with positive biomarker results to a specialist for further evaluation.

Evaluation of prostate cancer risk in men with PSA < 1.5

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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]