Estimating the risks and benefits of active surveillance protocols for prostate cancer: a microsimulation study.

OBJECTIVE

To estimate the increase in prostate cancer mortality (PCM) and the reduction in overtreatment resulting from different active surveillance (AS) protocols, compared with treating men immediately.

PATIENTS AND METHODS

We used a microsimulation model (MISCAN-Prostate), with the natural history of prostate cancer based on European Randomized Study of Screening for Prostate Cancer data. We estimated the probabilities of referral to radical treatment while on AS, depending on disease stage, using data from the Johns Hopkins AS cohort. We sampled 10 million men, representative of the US population, and projected the effects of applying AS protocols that differed by time between biopsies and compared these with the effects of treating men immediately.

RESULTS

We found that AS with yearly follow-up biopsies for men with low-risk prostate cancer (≤ T2a stage and Gleason 6) increases the probability of PCM to 2.6% (1% increase) and reduces overtreatment from 2.5 to 2.1% (18.4% reduction). With biopsies every 3 years after the first year, PCM increases by 2.3% and overtreatment reduces from 2.5 to 1.9% (30.3% reduction). The inclusion of men in the intermediate-risk group (> T2a stage or Gleason 3+4) in AS protocols increases PCM by 2.7% and reduces overtreatment from 2.5 to 2.0% (23.1% reduction). These results may not apply to African-American men.

CONCLUSIONS

Offering AS to men with low-risk prostate cancer is relatively safe. Increasing the biopsy interval from yearly to up to every 3 years after the first year will significantly reduce overtreatment among men in the low-risk group, with limited PCM risk.