Introduction

The Michigan Prostate Score (MiPS) is a validated and commercially available early detection test for prostate cancer combining serum PSA with urinary PCA3 and T2:ERG expression. This novel biomarker reports individual patient risk estimates for biopsy detection of any MiPS and of high-grade (Gleason score >6) prostate cancer HG MiPS. We investigated the impact of MiPS on clinical decision-making and prostate biopsy frequency rates and correlated MiPS and HG MiPS with final biopsy pathology results._x000D_ _x000D_ _x000D_ _x000D_ _x000D_ _x000D_

Methods

MiPS testing was offered to men referred for initial or repeat prostate biopsy at a single, tertiary institution as an alternative to proceeding directly to a biopsy between October 2013 and January 2015. Patient characteristics, PSA, PCA3, T2:ERG, and biopsy pathology were analyzed to see how MiPS and HG MiPS risk prediction models affected the decision for prostate biopsy as well as biopsy pathology. One-way ANOVA was used to correlate MiPS scores with biopsy rates and clinical outcomes.

Results

149 men underwent MiPS testing, of whom 67.8% had not undergone a prior prostate biopsy. Median age was 65.2, and median PSA was 9.5 ng/ml. The mean predicted risks for detection of any and high-grade cancer were 41.5% and 26.0%, respectively. The 73 men (49%) who proceeded to prostate needle biopsy had higher MiPS (52.7% vs. 30.7%, p<0.001) and HG MiPS scores (35.2% vs. 18.2%, p<0.001) than those who did not undergo biopsy. Among those biopsied, MiPS, HG MiPS, PCA3, and T2:ERG were significantly higher in those with cancer (all p<0.05) found on biopsy. PSA alone was not associated with cancer diagnosis (p=0.82).

Conclusions

The combination of urinary PCA3 and T2:ERG in a test panel for prostate cancer reduced the use of prostate biopsy by 51% among men referred for prostate biopsy. MiPS and MiPS HG were closely correlated with the presence of any cancer and high-grade cancer, respectively. These findings support the clinical utility and validity of MiPS for stratifying prostate cancer risk and guiding high-yield biopsy utilization.

Funding

None