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 offinding 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.