T. Y. T. De Souza1, S. Tanguay1, M. Duclos1, A. Aprikian1, S. L. Faria1, W. Kassouf1, J. M. G. Tsui2, R. Sanchez-Salas1, L. Souhami1, and F. Cury1; 1McGill University Health Centre, Montreal, QC, Canada, 2McGill University Health Center, Montréal, QC, Canada
Purpose/Objective(s): Stereotactic ablative body radiotherapy (SABR) is an emerging non-invasive treatment option for primary renal cell carcinoma (RCC). This study presents findings on the efficacy and toxicity in patients with RCC who underwent treatment at a single center using SABR to the lesion in the kidney. Materials/
Methods: We retrospectively evaluated the charts of patients treated with ablative RT doses to the kidney. Information was collected on demographic and clinical data, treatment planning, oncological outcomes, and image response evaluation (Response Evaluation Criteria in Solid Tumors [RECIST] v1.1). Survival outcomes were analyzed using Kaplan-Meier estimates and Cox proportional-hazards regression. Data on toxicity are reported according to Common Terminology Criteria for Adverse Events version 4.0, and urinary function was monitored through pre- and post-treatment estimated Glomerular Filtration Rate (eGFR) and creatinine levels. Results: Between 2011 and 2023, a total of 72 patients were identified, and 21 patients were excluded from this analysis due to primary transitional cell carcinoma histology. Among the 51 patients analyzed, seven presented with metastatic RCC. The median follow-up was 30 months (interquartile range [IQR] 13–75), and the median age was 78 years (IQR 69–84). The median tumour size was 4.48 cm (IQR 3.27–4.87 cm), and sixteen had hilar involvement. Patients were treated with different dose-fractionation schemes chosen by the treating radiation oncologist: 40 Gy in five fractions (69%), 45 Gy in three fractions (6%), or 24-26 Gy in one fraction (25%); depending on the size and location of the lesion. The mean (± SD) estimated glomerular filtration (eGFR) rate before SABR was 48.8 ± 13.1 mL per minute, which decreased by 3.5 ± 8.2 mL per minute (P = .005). The mean (± standard deviation) serum creatinine levels before SABR were 124.3 ± 99.3 µmol/L, which increased by 8.2 ± 36.6 µmol/L (P = .077). No patient required dialysis during follow-up. The 2-year OS, LRFS, and DMFS are 81.3%, 93.3%, and 87.7%, respectively. There were no grade 3 toxic effects or treatment-related deaths and only one (2%) patient developed an acute grade 2 chest pain. Conclusion: SABR is a safe and effective non-invasive treatment for primary RCC with minimal impact on renal function and very limited side effects. Our data support SABR as a viable option for patients unwilling or unfit to undergo surgery.
