Purpose: Few validated clinical tools currently exist to standardize the frequency of biopsies for men on active surveillance for low risk prostate cancer. We determined predictors of biopsy reclassification at specific time points after enrollment on active surveillance.
Materials and methods: We identified men with clinically low risk prostate cancer prospectively enrolled on active surveillance at the University of California, San Francisco between 2000 and 2016. Biopsy reclassification was defined as Gleason Grade Group 2 or greater on subsequent biopsy. Multivariable Cox proportional hazards regression models were used to identify factors associated with risk of biopsy reclassification at first surveillance biopsy and 1 to 3, 3 to 5 and 5 to 10 years after enrollment, adjusting for clinicodemographic factors, PI-RADS® (Prostate Imaging Reporting and Data System) score and genomic testing.
Results: A total of 1,031 men were included in the study. On multivariable analysis biopsy reclassification was associated with prostate specific antigen density 0.15 or greater (HR 3.37, 95% CI 1.83-6.21), percentage biopsy cores positive (HR 1.27, 95% CI 1.05-1.54) and high genomic score (HR 2.81, 95% CI 1.21-6.52) at first surveillance biopsy and also at 1 to 3 years, after adjustment. Prostate specific antigen density 0.15 or greater (HR 2.36, 95% CI 1.56-3.56) and prostate specific antigen kinetics (HR 2.19, 95% CI 1.43-3.34) were associated with reclassification at 3 to 5 years. A PI-RADS 4-5 score was not associated with biopsy reclassification at any time point.
Conclusions: High genomic score, prostate specific antigen kinetics and prostate specific antigen density 0.15 or greater were associated with reclassification within 3 years of commencing active surveillance, and prostate specific antigen kinetics and prostate specific antigen density 0.15 or greater remained associated with reclassification at 5 years after diagnosis.
Keywords: biopsy; genomics; multiparametric magnetic resonance imaging; prostate-specific antigen; watchful waiting.