SABR for oligometastatic renal cell carcinoma

Abstract

Stereotactic ablative body radiotherapy (SABR) aims to accurately deliver a higher than conventional dose of radiotherapy to a well-defined target tumour incorporating advanced immobilisation and imaging techniques. SABR is an emerging treatment option for primary kidney cancer especially when surgery is contraindicated. Increasingly, SABR is being incorporated into the management of low-volume stage IV kidney cancers to delay the need for systemic therapy or to prolong the duration of ongoing systemic treatment. This review will evaluate the evidence and limitations of SABR for oligometastatic renal cell carcinoma.

Keywords: Oligometastasis; Renal cell carcinoma; Stereotactic ablative body radiotherapy; Stereotactic ablative radiotherapy.

Fig. 1

Role of SABR for RCC oligometastases and oligoprogression. A) De-novo oligometastatic disease is defined as the first presentation with 1–5 metastatic lesions, where all sites must be safely treatable. B) Oligoprogression occurs when polymetastatic disease (>5 metastases) is treated with systemic treatment (with or without local treatment) and subsequently 1–5 new and/or growing metastases develop during systemic therapy. C) Both situations and several other disease states as defined by The European Society for Radiotherapy and Oncology and European Organisation for Research and Treatment of Cancer consensus recommendation can be managed with SABR to delay or prevent the need for systemic therapy..

Fig. 2

Novel imaging modalities with higher sensitivity and specificity may lead to improved patient selection and outcomes for patients with RCC oligometastases. A) Standard imaging such as CT and bone scan may miss smaller oligometastases. B) In the future, novel imaging modalities may be able to detect smaller oligometastases for targeting with SABR. C) This can reduce the rates of local and distant progression after SABR. D) With standard imaging, polymetastases are more likely to be falsely diagnosed as oligometastases resulting in suboptimal patient selection for SABR. E) Novel imaging modalities with superior sensitivity may lead to improved accuracy in diagnosis and improved management.