Outcomes of stereotactic radiotherapy for cranial and extracranial metastatic renal cell carcinoma: A systematic review

Background. Stereotactic radiotherapy is a non-invasive, ablative technique which may be particularly effective in treating metastatic renal cell carcinoma (RCC). The study objective was to analyse outcomes and toxicity of stereotactic radiotherapy in metastatic RCC. Material and methods. Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, a systematic review of Medline was performed in March 2013. Exclusion criteria included mixed histology studies and case series. Local control, overall survival and toxicities were analysed. Results. From 148 publications identified, 16 and 10 publications for cranial and extracranial metastatic RCC met inclusion criteria, respectively. There were 810 intracranial patients and 2433 targets. The weighted local control was 92%. Overall survival ranged from 6.7 to 25.6 months. Significant Grade 3-4 toxicity ranged from 0% to 6%. The weighted rate of treatment-related mortality was 0.6%, all secondary to intratumoral haemorrhage. There were 389 extracranial patients and 730 targets. The weighted local control was 89%. Median overall survival ranged from 11.7 to 22 months. Grade 3-4 toxicity ranged from 0% to 4%. Treatment-related mortality was 0.5%. Conclusion. Stereotactic radiotherapy is associated with excellent local control and low rates of toxicity for intracranial and extracranial metastatic RCC. Future randomised studies are required to confirm the additional benefit of Stereotactic Ablative Body Radiotherapy (SABR) above standard conservative or palliative approaches.