S1144
Clinical - Urology
ESTRO 2026
Purpose/Objective: The FASTRACK II clinical trial investigated the efficacy of SABR as a novel non-invasive alternative for primary renal cell cancer (RCC) in non-surgical candidates. Herein, we report the long-term outcome data. Material/Methods: This non-randomized, intergroup (TROG/ANZUP) phase II study was activated in seven centres in Australia and one centre in the Netherlands. Eligible patients of had biopsy confirmed diagnosis of primary RCC histology and were medically inoperable, high risk, or declined surgery, had an ECOG performance ≤ 2, T1-T2a and N0-N1 disease. The primary outcome was local control after SABR according to RECIST 1.1. SABR was prescribed as 24Gy in one fraction for tumors ≤ 4 cm in maximum diameter, or 42Gy in three fractions for tumors >4 cm. Safety was evaluated using Common Toxicity Criteria for Adverse Events (CTCAE) version 4.03. Trial ID: NCT02613819. Results: Seventy patients were enrolled between 28 Jul 2016 and 27 Feb 2020 with a median follow-up of 62 months. Median age was 77 years. Prior to enrolment, 49 patients (70%) had documented serial growth after initial surveillance. Forty-nine were male (70%), median BMI was 32 and median R.E.N.A.L. complexity score was 8. Median (interquartile range) tumour size was 4.6cm [3.7-5.5], with 24(35%) having T1a, 39(56%) T1b, 6(9%) T2 and 1(1%) T3a disease. One patient (1%) had N1 involvement. Local control was 100% throughout the lifetime of the trial. Cancer-specific survival was 100% throughout the lifetime of the trial. Linear mixed model estimates (95% CI) of eGFR were 61.1 mLs/min (56.5 - 65.6) at baseline, steadily declining to 46.5 (41.8 - 51.1) at 2 years, plateauing thereafter. Seven (10%) patients experienced grade 3 treatment-related adverse events (TRAE), with no grade 4 or 5 events observed. There was no new long- term safety signal noted. Common (>10%) TRAE of any grade were flank pain (n=32), nausea (n=21) and fatigue (n=43). Conclusion: Long-term follow-up confirms excellent oncological and safety outcomes in this first multicentre trial of a non-surgical RCC cohort. SABR was an effective treatment strategy with no observed local failures or cancer-related deaths in this cohort with predominantly ≥ T1b disease. We observed no new safety concerns and renal function was preserved in the long-term. For patients who are surgical candidates, these findings warrant the design of randomized clinical trial of SABR versus surgery for primary RCC. Keywords: Renal cell carcinoma, SBRT, SRS
fraction regimen and demonstrating superiority over the CT-LINAC two-fraction regimen. These findings support the safety of two-fraction MR-guided adaptive radiotherapy for localised prostate cancer. Follow-up for late toxicity, patient-reported outcomes, and oncologic outcomes is ongoing. Keywords: Prostate cancer, SABR, MR-Linac Proffered Paper 505 Final Results of the TROG 15.03 FASTRACK II Clinical Trial: Stereotactic Ablative Body Radiotherapy (SABR) for Primary Kidney Cancer Shankar Siva 1,2 , Muhammad Ali 1,2 , Nicholas Hardcastle 1,2 , Daniel Moon 3,4 , Tomas Kron 1,5 , Braden Higgs 6 , Farshad Foroudi 7,8 , Jeremy Ruben 9 , Jarad Martin 10 , Swetha Sridharan 10 , Rebecca Montgomery 11 , Ryan Davey 11 , Charles Lin 12,13 , Mark Shaw 1,2 , Sree Appu 14 , Ben GL Vanneste 15 , Declan Murphy 3,2 , Nathan Lawrentschuk 3,16 , Simon Wood 17 , David Pryor 17 , Mathias Bressel 18,2 1 Department of Radiation Oncology, Peter MacCallum Cancer Centre, Melbourne, Australia. 2 Sir Peter MacCallum Department of Oncology, University of Melbourne, Melbourne, Australia. 3 Division of Cancer Surgery, Peter MacCallum Cancer Centre, Melbourne, Australia. 4 Royal Melbourne Clinical School, University of Melbourne, Melbourne, Australia. 5 Centre of Medical Radiation Physics, University of Wollongong, Wollongong, Australia. 6 Department of Radiation Oncology, Royal Adelaide Hospital, Adelaide, Australia. 7 Department of Radiation Oncology, Olivia Newton- John Cancer Centre, Heidelberg, Australia. 8 Medical Imaging and Radiation Sciences, School of Primary and Allied Health Care, Monash University, Melbourne, Australia. 9 Department of Radiation Oncology, Alfred Health, Melbourne, Australia. 10 Department of Radiation Oncology, Calvary Mater Newcastle, Waratah, Australia. 11 Research Development, TransTasman Radiation Oncology Group (TROG) Cancer Research, Newcastle, Australia. 12 Department of Radiation Oncology, Royal Brisbane and Women's Hospital, Brisbane, Australia. 13 School of Medicine, University of Queensland, Brisbane, Australia. 14 Department of Urology, Cabrini Research Division, Melbourne, Australia. 15 Department of Radiation Oncology, MAASTRO-clinic, Maastricht, Netherlands. 16 Department of Surgery, University of Melbourne, Melbourne, Australia. 17 Department of Urology and Radiation Oncology, Princess Alexandra Hospital, Woolloongabba, Australia. 18 Department of Biostatistics and Clinical Trials, Peter MacCallum Cancer Centre, Melbourne, Australia
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