Prognostic and Predictive Biomarkers in Oligometastatic Disease.

Metastatic lesions are largely responsible for cancer-related deaths and are synonymous with a poor prognosis. However, this is not always true for patients with oligometastases whose disease may be amenable to curative-intent local therapies. It has been proposed that an "intermediate state" (oligometastasis) exists in between locoregional and advanced disease states; however, the clinical definition of oligometastasis varies, and there is limited understanding of how tumor biology differs between oligometastases and polymetastases. There is evidence that local therapies can extend survival in patients with oligometastases, yet patient selection for local intervention and/or systemic therapy remains a challenge. Prognostic and predictive biomarkers of oligometastatic disease are strongly needed to identify patient candidates most likely to gain survival benefit from local therapies and to aid in the incorporation of ablative treatments in the context of existing systemic therapies.