Hospital variation in cancer treatments and survival outcomes of advanced melanoma patients: Nationwide quality assurance in the Netherlands.

e18641 Background: The introduction of new systemic treatments for advanced melanoma has markedly changed the outcome patients with metastatic melanoma. To assure high quality care treated in Dutch centers, hospital variation treatment patterns and outcomes are evaluated Melanoma Treatment Registry. aim this study was to assess center 2-year survival probabilities diagnosed between 2013-2017 Netherlands. Methods: We selected unresectable stage IIIC or IV melanoma, registered Centers’ performance on compared by means a multivariable Cox proportional hazards model random effect ID. Variation centers expressed median hazard ratios. Therapy BRAF/MEK inhibitors, anti-PD-1 antibodies ipilimumab plus nivolumab added as time dependent covariate influence therapies variation. Results: Between 2013-2017, 3820 were For 2013-2015, significant observed. Median ratio 1.17 (95%CI: 1.09-1.31) 2013-2015 after correcting case-mix nivolumab. Use had up (hazard = 0.83, 95%CI (0.73-0.94)) no use reference. From 2016 onwards, difference 2-years observed centers. Conclusions: different cancer an A platform such Registry, which collaborate have insight results fast implementation clinical developments across all