Stereotactic Radiotherapy as a Treatment Option for Renal Tumors in the Solitary Kidney: A Multicenter Analysis from the IROCK

Purpose:Stereotactic ablative radiotherapy is an emerging treatment for renal cell carcinoma. Our study objective was to evaluate this therapy in patients with a solitary kidney, focusing on oncologic and renal function outcomes.Materials and Methods:We pooled individual patient data from 9 IROCK (International Radiosurgery Oncology Consortium for Kidney) institutions in Germany, Australia, the United States of America, Canada and Japan. Median followup was 2.6 years. Baseline characteristics and outcomes were compared between the solitary and bilateral kidney cohorts. Predictors of renal function after stereotactic ablative radiotherapy were assessed by logistic regression modeling.Results:A total of 81 patients with a solitary kidney underwent stereotactic ablative radiotherapy. Mean age was 67.3 years and 97.5% of patients had good performance status, including ECOG (Eastern Cooperative Oncology Group) 0-1 or KPS (Karnofsky Performance Status) 70% or greater. Median tumor diameter was 3.7 cm (IQR 2.5–4...