Timo Soeterik

53 Active Surveillance: Follow-up DISCUSSION In this study, we observed significant variation in AS protocol adherence between six large teaching hospitals in the Netherlands. In the overall population, 43% of the patients on AS received follow-up concordant with PRIAS. These are important findings, as they confirm our hypothesis that AS follow-up is less strict in daily clinical practice. Results from a large number of prospective AS cohorts have been published in the literature. 12,14–21 However, results for compliance rates with the respective follow-up protocols are limited. We identified two other study groups that performed comparable research. Our findings are in line with their results, as Luckenbaugh et al 22 also observed limited protocol adherence in a real-world cohort treated with AS at collaborating urological practices in Michigan (MUSIC). The authors reported that 26.5% of the patients who remained on AS for a minimum of 2 yr had follow-up compliant with the National Comprehensive Cancer Network guidelines. 22 The PRIAS study group reported that 91% of patients complied with all PSA visits and that 81% of men complied with the 1-yr prostate biopsy. 13 Overall percentages in our cohort were lower, as we observed that 74% of patients (706/958) had concordant PSA testing and 63% (570/912) complied with the first repeat biopsy. The differences between the PRIAS cohort and the real-world populations described in the present study and the MUSIC study indicate that there is a substantial gap regarding AS protocol adherence between the research setting and daily practice. The size of this gap may also differ at an institutional level, as significant differences between institutions were observed in both studies. Noncompliance with AS protocols is understandable, as biopsies are often considered painful by patients. 13 Moreover, biopsies are associated with several complications such as pain, hematuria, urinary tract infections and even urosepsis. 23 Given the significant burden, costs, and time associated with frequent monitoring, we have to deliberate on the intensity of AS follow-up schedules. However, it remains challenging to determine for whom and to what extent the intensity of AS follow-up schedules can be reduced. Given the higher risk of missing the window of curability, low-intensity monitoring may not be a safe option for PRIAS-ineligible patients. However, we found no significant difference in the rate of metastasis between discordant and concordant monitoring in the PRIAS- eligible group. This suggests that patients who can be classified with the lowest risk at diagnosis might be candidates for a less intensive follow-up schedule without being at risk of worsening their prognosis. We did not observe a higher rate of metastasis among patients noncompliant with the PRIAS repeat biopsy schedule in comparison to compliant patients. The lack of association between biopsy noncompliance and prognosis can be partly explained by the fact that most of these men did not have rapidly increasing PSA (65% had a PSADT of >3 yr). Of the patients who were compliant, 54% had a PSADT of <3 yr, indicating that repeat biopsies were performed more frequently in cases with faster rising PSA. This indicates that the decision to repeat prostate biopsy was partly based on serial serum PSA results instead of what the protocol advised. This can be further explained by taking hospital 1 as an 3