Follow-up in Active Surveillance for Prostate Cancer: Strict Protocol Adherence Remains Important for PRIAS-ineligible Patients

Abstract

Background: Active surveillance (AS) is a safe treatment strategy for men with low-risk prostate cancer (PC) when performed in a research setting using strict follow-up. However, less is known about the protocol adherence and outcomes for AS in real-world practice.

Objective: To evaluate Prostate Cancer Research International Active Surveillance (PRIAS) protocol adherence in a real-world cohort and to relate follow-up intensity to oncological safety.

Design, setting, and participants: Patients with biopsy-detected PC diagnosed from 2008 to 2014 treated with AS at six teaching hospitals in The Netherlands.

Intervention: AS included regular prostate-specific antigen (PSA) testing (every 3-6mo) combined with a confirmatory biopsy 1yr after diagnosis and every 3yr thereafter.

Outcome measurements and statistical analysis: The proportions of patients complying with the PRIAS biopsy and PSA monitoring protocol were determined. We assessed if PRIAS-discordant follow-up was associated with a higher risk of metastasis compared with PRIAS-concordant follow-up using Cox regression analysis. Analysis was performed for separate risk groups (PRIAS-eligible and PRIAS-ineligible) on the basis of the PRIAS inclusion criteria.

Results and limitations: Of all patients on AS for >6mo, 706/958 (74%) had PRIAS-concordant PSA monitoring. Overall concordant follow-up (PSA and repeat biopsy) was observed in 415/958 patients (43%). The percentage of patients with overall concordant follow-up varied between hospitals (range 34-60%; p<0.001). Among PRIAS-ineligible patients, PRIAS-discordant PSA monitoring was associated with a higher risk of developing PC metastases during AS compared with patients with concordant follow-up (hazard ratio 5.25, 95% confidence interval 1.02-27.1). In the PRIAS-eligible population, we found no significant differences regarding rates of metastases between patients with discordant and concordant follow-up.

Conclusions: We observed substantial variation in AS follow-up intensity between large urological practices in the Netherlands. Overall, 43% of patients on AS in daily clinical practice receive PRIAS-concordant follow-up. Noncompliance with the PRIAS follow-up protocol was associated with a higher rate of metastasis among PRIAS-ineligible patients, indicating that strict protocol adherence is important when these patients opt for AS.

Patient summary: Fewer than half of patients with prostate cancer on active surveillance are monitored according to the follow-up protocol of the largest ongoing active surveillance study. Lower-intensity monitoring may be less safe for patients who are not in the lowest risk group.

Keywords: Active surveillance; Prostate cancer; Protocol adherence.