Objectives: To compare the oncological outcomes of patients with upper tract urothelial carcinoma (UTUC) undergoing kidney-sparing surgery (KSS) with fiber-optic (FO) vs digital (D) ureteroscopy (URS). To evaluate the oncological impact of image enhance technologies such as narrow-band imaging (NBI) and Image 1S in patients with UTUC. Materials and methods: The CROES-UTUC registry is an international, multicenter, cohort study prospectively collecting data on patients with UTUC. Patients undergoing flexible FO or D-URS for diagnostic or diagnostic and treatment purposes have been included. Differences between groups in terms of overall survival (OS) and disease-free survival (DFS) have been evaluated. Results: The CROES registry included 2380 patients from 101 centers and 37 countries, of whom 401 patients underwent URS (FO-URS:186 and D-URS:215). FO-URS were performed more frequently for diagnostic purposes while D-URS when a combined diagnostic and treatment strategy was planned. Intraoperative and postoperative complications did not differ between groups. 5-years OS and DFS rates were 91.5% and 66.4% respectively. Mean OS was 42 months for patients receiving FO-URS and 39 months for those undergoing D-URS (p=0.9); mean DFS was 28 months in the FO group and 21 months in the D group (p<0.001). In patients who received URS with treatment purposes, no difference regarding OS (p=0.9) and DFS (p=0.7) were observed. NBI and Image 1S technologies did not improve OS nor DFS over D-URS. Conclusions: D-URS did not provide any oncological advantage over FO-URS. Similarly, no differences in terms of OS and DFS were found when image enhance technologies were compared to D-URS. These findings underline the importance of surgeon skills and experience and reinforce the need for the centralization of UTUC care.