Purpose: The GPS (Oncotype Dx® Genomic Prostate Score) test is a RNA expression assay which can be performed on prostate biopsies. We sought to determine whether the GPS was associated with an increased risk of adverse pathology findings in men enrolled on active surveillance who later underwent radical prostatectomy.
Materials and methods: We identified all patients on active surveillance at University of California-San Francisco who had Gleason score 3 + 3 or low volume (33% or fewer positive cores) Gleason score 3 + 4 prostate cancer, GPS testing at diagnostic or confirmatory biopsy, clinical stage T1/T2, prostate specific antigen less than 20 and a clinical CAPRA (Cancer of the Prostate Risk Assessment) score less than 6. The primary outcome was adverse pathology, defined as Gleason score 4 + 3 or greater, stage pT3a or greater, or pN1. The secondary outcome was biochemical recurrence, defined as 2 consecutive prostate specific antigen measurements greater than 0.05 ng/ml following radical prostatectomy.
Results: Of the 215 men 179 (83%) were at low risk and 36 (17%) were at intermediate risk by CAPRA scoring. The median GPS was 26.4 (IQR 18.8-34.6). On multivariate analysis a higher GPS was associated with an increased risk of adverse pathology at delayed radical prostatectomy (HR/5 units 1.16, 95% CI 1.06-1.26, p <0.01). A higher GPS was also associated with an increased risk of biochemical recurrence (HR/5 units 1.10, 95% CI 1.00-1.21, p=0.04).
Conclusions: In patients who undergo radical prostatectomy after a period on active surveillance, as in those who undergo immediate prostatectomy, a higher GPS is associated with an increased risk of adverse pathology. The GPS is also associated with biochemical recurrence following radical prostatectomy in such patients.
Keywords: clinical; genomics; pathology; prostate-specific antigen; prostatectomy; watchful waiting.