Stereotactic Body Radiotherapy (SBRT) for the Treatment of Primary Localized Renal Cell Carcinoma: A Systematic Review and Meta-Analysis

Abstract

Context: Surgery is the gold standard for the local treatment of primary renal cell carcinoma (RCC), but alternatives are emerging. We conducted a systematic review and meta-analysis to assess the results of prospective studies using definitive stereotactic body radiotherapy (SBRT) to treat primary localised RCC. Evidence acquisition: This review was prospectively registered in PROSPERO (CRD42023447274). We searched PubMed, Embase, Scopus, and Google Scholar for reports of prospective studies published since 2003, describing the outcomes of SBRT for localised RCC. Meta-analyses were performed for local control (LC), overall survival (OS), and rates of adverse events (AEs) using generalised linear mixed models (GLMMs). Outcomes were presented as rates with corresponding 95% confidence intervals (95% CIs). Risk-of-bias was assessed using the ROBINS-I tool. Evidence synthesis: Of the 2983 records, 13 prospective studies (n = 308) were included in the meta-analysis. The median diameter of the irradiated tumours ranged between 1.9 and 5.5 cm in individual studies. Grade ≥ 3 AEs were reported in 15 patients, and their estimated rate was 0.03 (95%CI: 0.01–0.11; n = 291). One- and two-year LC rates were 0.98 (95%CI: 0.95–0.99; n = 293) and 0.97 (95%CI: 0.93–0.99; n = 253), while one- and two-year OS rates were 0.95 (95%CI: 0.88–0.98; n = 294) and 0.86 (95%CI: 0.77–0.91; n = 224). There was no statistically significant heterogeneity, and the estimations were consistent after excluding studies at a high risk of bias in a sensitivity analysis. Major limitations include a relatively short follow-up, inhomogeneous reporting of renal function deterioration, and a lack of prospective comparative evidence. Conclusions: The short-term results suggest that SBRT is a valuable treatment method for selected inoperable patients (or those who refuse surgery) with localised RCC associated with low rates of high-grade AEs and excellent LC. However, until the long-term data from randomised controlled trials are available, surgical management remains a standard of care in operable patients.