3317 - Renal Function Preservation after Stereotactic Ablative Radiotherapy for Primary Renal Cell Carcinoma: A Multicenter Real-World Experience
Presenter(s)
W. Majewski1,2, M. Bilski3,4, W. Kamzol5,6, K. Stawiski7,8, G. Majewski1,9, K. Konopa10, A. Ciepiela1, and B. Tomasik10,11; 1Radiotherapy Department, Maria Sklodowska-Curie National Research Institute of Oncology, Gliwice, Poland, 2Department of Oncology, Faculty of Medical Sciences in Zabrze, Medical University of Silesia, Katowice, Poland, 3Department of Radiotherapy, Medical University of Lublin, Lublin, Poland, 4Radiotherapy Department, Affidea Nu-med Centre of Oncology Diagnostics and Therapy, Zamosc, Poland, 5Department of Genitourinary Oncology, Maria Sklodowska-Curie National Research Institute of Oncology, Warsaw, Poland, 6Department of Radiotherapy, Maria Sklodowska-Curie National Research Institute of Oncology, Warsaw, Poland, 7Department of Biostatistics and Translational Medicine, Medical University of Lódz, Lódz, Poland, 8Department of Brachytherapy and General Oncology, Copernicus Memorial Hospital, Lódz, Poland, 9Student Research Group at the Department of Oncology, Faculty of Medical Sciences in Zabrze, Medical University of Silesia, Katowice, Poland, 10Department of Oncology and Radiotherapy, Medical University of Gdansk, Gdansk, Poland, 11Centre for Experimental Cardiooncology, Medical University of Gdansk, Gdansk, Poland
Purpose/Objective(s): Stereotactic ablative radiotherapy (SABR) is an established non-invasive treatment option for patients with primary renal cell carcinoma (RCC) who are not candidates for surgery. Preservation of renal function is a central therapeutic objective in this population, particularly in those with limited baseline renal reserve. The primary objective of this study was to evaluate renal function outcomes following SABR, assessed by changes in estimated glomerular filtration rate (eGFR) and the incidence of clinically meaningful renal function decline. Oncologic outcomes and treatment-related toxicity were analyzed as secondary endpoints.
Materials/Methods: Patients treated with SABR for primary RCC between 2016 and 2025 were retrospectively analyzed across five Polish centers with expertise in uro-oncology and stereotactic radiotherapy. Histopathologic confirmation was not mandatory in cases with unequivocal radiologic features of malignancy. Patient and tumor characteristics, treatment regimens, renal function parameters, local control (LC), overall survival (OS), and toxicity graded according to CTCAE were evaluated. Time-to-event outcomes were estimated using the Kaplan-Meier method.
Results: Forty patients were included, with a median age of 75 years (IQR: 63-82). Most were medically inoperable (n = 30), while 10 declined surgery. Baseline mean and median eGFR were both 60.0 mL/min/1.73 m² (± 22.1; IQR: 47.0-76.5). SABR was delivered to a solitary kidney in 14 patients. At 12 months, the mean and median change in eGFR were -4.8 (± 9.1) mL/min/1.73 m² and -1.0 (IQR: -9.0-2.0) mL/min/1.73 m², respectively, indicating overall preservation of renal function. A clinically meaningful decline in eGFR (=15 mL/min/1.73 m²) occurred in two patients. Two patients required dialysis during follow-up; both had severe pre-existing chronic kidney disease (baseline eGFR <10 mL/min/1.73 m²). One was already receiving dialysis prior to SABR, and the second initiated previously planned dialysis one month after treatment. No dialysis events were attributable to SABR. After a median follow-up of 11 months, 1-year LC and OS rates were 94% and 92%, respectively. Early grade 1 adverse events (fatigue, nausea, pain) occurred in seven patients, with one case of grade 2 fatigue. One late grade 1 pain event was observed. No grade =3 toxicity was reported.
Conclusion: SABR for primary renal cell carcinoma demonstrated preservation of renal function in the majority of patients, with a low incidence of clinically meaningful eGFR decline (=15 mL/min) and no dialysis events attributable to treatment. Early oncologic outcomes, including 1-year local control and overall survival, were consistent with published literature on SABR in RCC, supporting its efficacy in this setting. These results reinforce SABR as a viable nephron-preserving treatment paradigm for patients with primary RCC who are unsuitable for surgery.