A systematic review of stereotactic radiotherapy ablation for primary renal cell carcinoma

OBJECTIVE To critically assess the use of stereotactic ablative body radiotherapy (SABR) for the treatment of primary renal cell carcinoma with particular focus on local control and toxicity outcomes. METHODS A systematic search on PubMed was performed in January 2012 independently by two radiation oncologists using structured search terms. Secondary manual searches were performed on citations in relevant publications and abstracts in major radiotherapy journals. Outcomes, techniques, biological doses and scientific rigour of the studies were analysed. RESULTS In total 10 publications (seven retrospective and three prospective) were identified. A wide range of techniques, doses and dose fractionation schedules were found. A total of 126 patients were treated with between one and six fractions of SABR. Median or mean follow-up ranged from 9 to 57.5 months. A weighted local control was reported of 93.91% (range 84%-100%). The weighted rate of severe grade 3 or higher adverse events was 3.8% (range 0%-19%). The weighted rate of grade 1-2 minor adverse events was 21.4% (range 0%-93%). The most commonly employed fractionation schedule was 40 Gy delivered over five fractions. CONCLUSIONS Current literature suggests that SABR for primary renal cell carcinoma can be delivered with promising rates of local control and acceptable toxicity. However, there was insufficient evidence to recommend a consensus view for dose fractionation or technique. This indicates the need for further prospective studies assessing the role of this technique in medically inoperable patients.