Safety and Efficacy of Stereotactic Ablative Radiation Therapy for Renal Cell Cancer: 24-Month Results of the RSR1 Phase 1 Dose Escalation Study

Purpose: Stereotactic body radiation therapy (SBRT) has become a new therapeutic option for primary renal cell carcinoma. However, treatment doses lack consistency in the literature. The primary objective of this study was to determine the maximum tolerated dose for renal cancer SBRT.Methods and Materials: This phase 1 multicentric dose-escalation study assessed 4 dose levels: 8 Gy x 4, 8 Gy x 5, 10 Gy x 4, and 12 Gy x 4. The primary objective of this study was to determine the maximal tolerated dose, defined by the occurrence of dose-limiting toxicity was defined as any acute side effect of grade >= 4 based on the Common Terminology Criteria for Averse Events, version 4.0.Results: From October 2010 to September 2017, 13 patients were enrolled. The median follow-up was 23 months. There was no dose-lim-iting toxicity in our study, and the highest dose was reached successfully. No acute or late toxic effects above grade 2 were seen. There was no significant alteration of renal function after treatment. At 24 months, 2 patients had partial response and the others had stable disease.Conclusions: After 24 months of follow-up, no dose-limiting toxicity was seen at any of the prescribed dose levels in our study. The findings suggest that our last dose level of 48 Gy in 4 12-Gy fractions can be considered safe and can be used in further studies.(c) 2022 American Society for Radiation Oncology. Published by Elsevier Inc. All rights reserved.

Automated summary

The purpose of this study was to determine the maximum tolerated dose for primary renal cell carcinoma treated with stereotactic body radiation therapy (SBRT). A multicentric phase 1 study was conducted using dose escalation, and it was found that there was no dose-limiting toxicity at the prescribed dose levels. The highest dose of 48 Gy in 4 fractions was deemed safe for further studies.