Stereotactic radiotherapy as a treatment option for renal tumours in the solitary kidney: a multicenter analysis from the International Radiosurgery Oncology Consortium for Kidney (IROCK).

AbstractPurpose:Stereotactic ablative radiotherapy (SABR) is an emerging treatment for renal cell carcinoma (RCC). Our study objective was to evaluate SABR in patients with a solitary kidney, focusing on oncological and renal function outcomes.Materials and Methods:Individual patient data from nine IROCK institutions in Germany, Australia, USA, Canada and Japan were pooled. Median follow-up was 2.6 years. Baseline characteristics and outcomes were compared between solitary and bilateral kidney cohorts. Predictors of post-SABR renal function were assessed by logistic regression modelling.Results:81 solitary kidney patients underwent SABR. Mean age was 67.3 years and 97.5% had good performance status (ECOG 0-1 or KPS ≥70%). Median tumour diameter was 3.7cm [IQR: 2.5-4.3], with 37% of tumours ≥4cm. Patients in the bilateral cohort (n=138) harbored larger tumours and were older (p<0.001) with lower baseline eGFR (p=0.024). In the solitary cohort, post-SABR eGFR decrease (mean±SD) was -5.8±10.8 mL/min (or -9%)...