Timo Soeterik

45 Active Surveillance: Follow-up BACKGROUND The principle of active surveillance (AS) is to avoid overtreatment of clinically insignificant prostate cancer (PCa) and to defer treatment until objective evidence of disease progression. 1 Favourable outcomes of AS in a trial setting have led to its widespread acceptance. 2–4 However, it remains challenging to identify men with indolent disease among those with progressive PCa at risk of missing the window of curability. The protocols of published AS studies adhere to the same principles: repeat prostate biopsies (intensity varying per protocol from yearly to every 3-4 yr) combined with regular prostate specific antigen (PSA) testing every 3–6 mo. 5 However, these monitoring protocols can be burdensome for patients, are time-consuming and costly. Moreover, repeat biopsies are unpleasant for the patient and bear a risk of bleeding and infection. It is therefore conceivable that AS protocols are not followed as strictly in daily practice as recommended by the prevailing guidelines. This hypothesis is supported by an inventory of real world practice patterns in the USA, which revealed that less than 13% of PCa patients undergo repeat biopsy beyond the first two years of AS. 6 Furthermore, a survey among European urologists indicated that 47% of those practicing AS do not use an official AS protocol nor is involved in a clinical AS trial. 7 Also, a nationwide survey in Japan showed that only 40.6% of the urologists performed a scheduled repeat biopsy at 1 yr after AS initiation. 8 The possible consequences of these AS protocol deviations with regard to oncological safety are for the most part unknown. This calls for research assessing the safety of lower-intensity AS monitoring. In the present study, we evaluated AS follow-up strategies for PCa in six large Dutch teaching hospitals covering up to 15% of PCa patients in the Netherlands. We will determine the proportions of patients that underwent follow-up testing according to the Dutch guidelines, which are based on the follow-up protocol of the Prostate Cancer International Active Surveillance (PRIAS) study. 9 Furthermore, we assessed if patients with low-intensity monitoring had a higher risk of missing the window of curability because of the development of metastatic PCa during AS. METHODS Study setting and data collection This study was conducted within the Santeon consortium, which consists of seven large nonacademic teaching hospitals in the Netherlands. During the study period, data for the AS cohorts from six of these seven hospitals were available. The study focuses on the same cohort of PCa patients on AS diagnosed between January 1, 2008 and December 31, 2014 on which we reported previously. 10 Data collection and analysis included initial age and tumour characteristics at diagnosis, dates of follow-up serum PSA tests, repeat biopsies, magnetic resonance imaging (MRI) of the prostate and metastasis rates. 11 3