Stereotactic body radiotherapy for oligoprogressive cancer.

Stereotactic body radiotherapy (SBRT) is a focused tumour treatment that produces high local control rates with low toxicity. Its use in metastatic cancer is evolving rapidly, with purported benefits in the oligometastatic setting and for better palliation of symptomatic disease. Another potential indication for SBRT is in the setting of oligoprogression, where there is progression of a solitary or a few tumours while all other tumours are responding or stable on a systemic therapy strategy. SBRT to the progressing "rogue" tumours may delay the need to start or change systemic therapy. This may have clinical benefits including improved progression-free/overall survival and quality of life for patients. This review will summarize the limited published data. More prospective clinical trials are urgently needed to better identify and quantify the potential clinical benefits.