Timo Soeterik

44 CHAPTER 3 ABSTRACT Background: Active surveillance (AS) is a safe treatment strategy for men with very low- risk prostate cancer (PCa), when performed in a research setting using strict follow-up. However, less is known about the protocol adherence and outcomes of AS in real-world practice. In this study, we will evaluate the Prostate Cancer Research International Active Surveillance (PRIAS) protocol adherence in a real-world cohort and relate follow-up intensity to oncological safety. Methods: Patients with biopsy-detected prostate cancer (PCa), diagnosed from 2008 until 2014, treated with active surveillance at six teaching hospitals in the Netherlands, were included. Proportions of patients complying with the PRIAS follow-up protocol (including PSA testing every 3-6 months combined with a confirmatory biopsy one year after diagnosis and every three years thereafter) 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: Of all patients on AS for >6 mo, 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 PCa 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.