**5. Conclusions**

In conclusion, hypo-fractionated MRgRT for large RCC resulted in high LC and very low toxicity rates. Gated treatment without the need for anesthesia or fiducials appeared well tolerated. Even in this group with large RCCs, daily plan re-optimization was not needed for the majority of patients, who can be identified upfront by a combined OAR V25Gy of ≤ 0.5 cc in the baseline plans. This is a favorable result since online MRgRT plan adaptation is a time-consuming procedure. In this group of patients, MRgRT delivery will be faster, and these patients could be candidates for further hypofractionation [30].

**Author Contributions:** Conceptualization, S.U.T., O.B., F.J.L., and A.M.E.B.; Methodology, O.B. and F.J.L.; Software, O.B. and F.J.L.; Formal analysis, S.U.T., O.B., and F.J.L.; Investigation, S.U.T and O.B.; Resources, S.U.T., S.S.O., A.M.v.d.W., and A.M.E.B.; Data curation, S.U.T., O.B., and F.J.L.; Writing—original draft preparation, S.U.T., O.B., F.J.L., and A.M.E.B.; Writing—review and editing, S.S., M.A.P., S.S.O., A.M.v.d.W., R.J.A.v.M., and B.J.S.; Visualization, S.U.T. and O.B.; Supervision, F.J.L. and A.M.E.B.; Project administration, S.U.T., O.B., F.J.L., and A.M.E.B. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research received no external funding.

**Conflicts of Interest:** O.B. reports personal fees from ViewRay Techonologies Inc. outside the submitted work. S.S. reports grants from ViewRay Inc, grants from Varian Medical Systems, grants and personal fees from AstraZeneca, personal fees from MSD, personal fees from Celgene, outside the submitted work. M.A.P. reports personal fees from ViewRay Technologies, Inc., outside the submitted work. B.J.S. reports grants and personal fees from ViewRay and grants from Varian Medical Systems outside the submitted work. F.J.L. reports personal fees from ViewRay outside the submitted work. A.M.E.B. reports grants from ViewRay Inc. during the conduct of the study, personal fees from ViewRay Inc., and other from ViewRay Inc. outside the submitted work.

#### **References**

1. Escudier, B.; Porta, C.; Schmidinger, M.; Rioux-Leclercq, N.; Bex, A.; Khoo, V.; Grünwald, V.; Gillessen, S.; Horwich, A.; ESMO Guidelines Committee. Renal cell carcinoma: ESMO Clinical Practice Guidelines for diagnosis, treatment and follow-up. *Ann. Oncol.* **2019**, *30*, 706–720. [CrossRef] [PubMed]


© 2020 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).
