Stereotactic ablative body radiotherapy (SABR) is a novel option to treat primary renal cell carcinoma (RCC). However, a high radiation dose may be received by the treated kidney, which may affect its function post-treatment. This study investigates the dose-effect relationship of kidney SABR with posttreatment renal function.
This was a prespecified secondary endpoint of the multicenter FASTRACK II clinical trial (NCT02613819). Patients received either 26 Gy in a single fraction (SF) for tumors with a maximal diameter of 4 cm or less, or 42 Gy in three fractions (multi-fraction (MF)) for larger tumors. To determine renal function change, 99mTc-DMSA SPECT/CT scans were acquired, and the glomerular filtration rate (GFR) was estimated at baseline, 12-, and 24-months post-treatment. Imaging datasets were rigidly registered to the planning CT where kidneys were segmented to calculate dose-response curves.
From 71 enrolled patients, data from 36 (51%) and 26 (37%) patients were included in this study based on availability of post-treatment data at 12- and 24-months, respectively. The ipsilateral kidney GFR decreased from baseline by 42% and 39% in the SF cohort, and by 45% and 62% in the MF cohort, at 12- and 24-months respectively (p-values < 0.03). The loss in renal function was 3.6±0.8% and 4.5±1.0% in the SF cohort, and 1.7±0.1% and 1.7±0.2% in the MF cohort, at 12- and 24-months respectively. The major loss in renal function occurred in high-dose regions, where dose-response curves converged to a plateau.
For the first time in a multicenter study, the dose-effect relationship at 12- and 24-months post-SABR treatment for primary RCC was quantified. Kidney function reduces linearly with dose up to 100 Gy BED3.
International journal of radiation oncology, biology, physics. 2024 Apr 26 [Epub ahead of print]
Mathieu Gaudreault, Nicholas Hardcastle, Price Jackson, Lachlan McIntosh, Braden Higgs, David Pryor, Mark Sidhom, Rachael Dykyj, Alisha Moore, Tomas Kron, Shankar Siva
Department of Physical Sciences, Peter MacCallum Cancer Centre, Melbourne, Victoria 3000, Australia; Sir Peter MacCallum Department of Oncology, the University of Melbourne, Victoria 3000, Australia. Electronic address: ., Department of Physical Sciences, Peter MacCallum Cancer Centre, Melbourne, Victoria 3000, Australia; Sir Peter MacCallum Department of Oncology, the University of Melbourne, Victoria 3000, Australia; Centre for Medical Radiation Physics, University of Wollongong, NSW, 2522, Australia., Department of Physical Sciences, Peter MacCallum Cancer Centre, Melbourne, Victoria 3000, Australia; Sir Peter MacCallum Department of Oncology, the University of Melbourne, Victoria 3000, Australia., Department of Physical Sciences, Peter MacCallum Cancer Centre, Melbourne, Victoria 3000, Australia., Department of Radiation Oncology, Royal Adelaide Hospital, South Australia, Australia; University of South Australia, South Australia, Australia., Princess Alexandra Hospital, Queensland, Australia., Liverpool Hospital, Liverpool, New South Wales, Australia., Trans Tasman Radiation Oncology Group, Waratah, NSW, 2298., Sir Peter MacCallum Department of Oncology, the University of Melbourne, Victoria 3000, Australia; Division of Radiation Oncology, Peter MacCallum Cancer Centre, Melbourne, Victoria 3000, Australia.