BACKGROUND: Active surveillance (AS) for prostate cancer (PCa) includes follow-up with serial prostate biopsies. The optimal biopsy frequency during follow-up has not been determined. The goal of this investigation was to use longitudinal AS biopsy data to assess if the frequency of biopsy could be reduced without substantially prolonging the time to detection of Gleason ≥7 disease.
METHODS: Using data from 1375 men with low-risk PCa enrolled in AS at Johns Hopkins, we developed a hidden Markov model (HMM) to estimate the probability of under sampling at diagnosis, the annual probability of grade progression, and the 10-year cumulative probability of reclassification or progression to Gleason ≥7. We simulated 1024 potential AS biopsy strategies for the 10 years following diagnosis. For each of these strategies the model predicted the mean delay in detection of Gleason ≥7 disease.
RESULTS: The model estimated 10-year cumulative probability of reclassification from Gleason 6 to Gleason ≥7 was 46.0%. The probability of under sampling at diagnosis was 9.8% and the annual progression probability for men with Gleason 6 was 4.0%. Based on these estimates, simulation of an annual biopsy strategy estimated the mean time to detection of Gleason ≥7 disease to be 14.1 months; however, several strategies eliminated biopsies with only small (<12 months) delays in detecting grade progression.
CONCLUSIONS: While annual biopsy for low-risk men on AS is associated with the shortest time to detection of Gleason ≥7 disease, several alternative strategies may allow for less frequent biopsy without sizable delays in detecting grade progression.
