12 per hospital, PN rates, complication rates, and completeness of data. Results: In total, 13045 surgically treated T1 tumours were included in the analyses. Over time, there was an increase in PNs (39.7% in 2012 to 44.9% in 2016). Missing information on post-operative complications appeared constant over the years (8.5-9%). PADUA score entry into the audit was initiated in 2016 and was included in 39% of cases recorded in 2016. A clear association was found between annual hospital volume and the proportion of T1 tumours treated with PN rather than RN (see figure 1-2), this association persisted after adjustment for PADUA complexity (figure 3a-b-c).The complication rate decreased with increasing surgical volume, for all patients as well as patients with PN (4a-b-c). Conclusions: Probability of treatment of T1 tumours with PN increased with increasing hospital volume, Journal of Clinical Urology 11(1S) Figure 3a. Best Academic Paper 4 Figure 3b. Best Academic Paper 4 Figure 1. Best Academic Paper 4 Figure 3c. Best Academic Paper 4 Figure 2. Best Academic Paper 4 whereas an inverse association of hospital volume with complication rate is found. These results show closer guideline adherence in higher volume centers and support the centralisation of specialist cancer surgical services to improve patient outcomes.