Projected outcomes of reduced-biopsy management of Grade Group 1 prostate cancer: implications for relabeling.

Abstract

Implications of relabeling Grade Group 1 prostate cancer as noncancer will depend on the recommended active surveillance strategy. Whether relabeling should prompt deintensifying, prostate-specific antigen (PSA)-based active monitoring approaches is unclear. We investigated outcomes of biopsy-based active surveillance strategies vs PSA-based active monitoring for Grade Group 1 diagnoses under different patient adherence rates. We analyzed longitudinal PSA levels and time to Grade Group 2 or higher reclassification among 850 patients with a diagnosis of Grade Group 1 disease from the Canary Prostate Active Surveillance Study (2008-2013). We then simulated 20 000 patients over 12 years, comparing Grade Group 2 or higher detection under biennial biopsy against 3 PSA-based strategies: (1) PSA (biopsy for PSA change ≥20% per year), (2) PSA plus magnetic resonance imaging (magnetic resonance imaging for PSA change ≥20% per year and biopsy for Prostate Imaging Reporting & Data System ≥3), and (3) predicted risk (biopsy for predicted upgrading risk ≥10%). Under biennial biopsies and 20% dropout to active treatment, 17% of patients had a 2-year or longer delay in Grade Group 2 or higher detection. The PSA strategy reduced the number of biopsies by 39% but delayed detection in 32% of patients. The PSA plus magnetic resonance imaging strategy reduced the number of biopsies by 52%, with a 34% delay. The predicted risk strategy reduced the number of biopsies by 31%, with only an 8% delay. These findings are robust to biopsy sensitivity and confirmatory biopsy. Prostate-specific antigen-based active monitoring could substantially reduce biopsy frequency; however, a precision strategy based on an individual upgrading risk is most likely to minimize delays in detection of disease progression. This strategy may be preferred if active surveillance is deintensified under relabeling, provided patient adherence remains unaffected.