Purpose: The OncotypeDx® GPS (Genomic Prostate Score®) is a 17-gene RNA expression assay intended to help guide treatment decisions in men diagnosed with prostate cancer. The PI-RADS™ (Prostate Imaging Reporting and Data System) version 2 was developed to standardize the risk stratification of lesions identified on multiparametric prostate magnetic resonance imaging. We sought to determine whether these tests are associated with an increased risk of biopsy upgrading in men on active surveillance.
Materials and methods: We identified all patients on active surveillance at the University of California-San Francisco who had low/intermediate risk prostate cancer (prostate specific antigen 20 ng/ml or less and clinical stage T1/T2) and Gleason score 6 disease who underwent multiple biopsies and had a GPS available and/or had undergone multiparametric prostate magnetic resonance imaging with an available PI-RADS version 2 score. The primary study outcome was biopsy upgrading, defined as an increase in the Gleason score from 3 + 3 to 3 + 4 or greater, which was analyzed by Cox proportional hazards regression.
Results: Of the men 140 had only GPS test findings, 169 had only a PI-RADS version 2 score and 131 had both data. Each 5-unit increase in the GPS was associated with an increased risk of biopsy upgrading (HR 1.28, 95% CI 1.19-1.39, p <0.01). PI-RADS scores of 5 vs 1-2 (HR 4.38, 95% CI 2.36-8.16, p <0.01) and 4 vs 1-2 (HR 2.62, 95% CI 1.45-4.76, p <0.01) were also associated with an increased risk of a biopsy upgrade. On subanalysis of patients with GPS and PI-RADS version 2 scores the GPS was associated with biopsy upgrading, adding value to the clinical covariates (partial likelihood ratio p = 0.01).
Conclusions: A higher GPS or a PI-RADS version 2 score of 4 or 5 was associated with an increased risk of biopsy upgrading.