SBRT and the treatment of oligometastatic disease

Abstract

For patients with metastatic cancer, there is significant variation in the amount of time from diagnosis to disease progression or death. For physicians, predicting the duration of this interval can be difficult. The clinical course for these patients is dependent on myriad factors including the primary histology, size, and location of metastatic lesions. Attempts have been made to model prognosis based on other factors such as response to neoadjuvant chemotherapy and volume of disease. A distinct clinical state of metastases with low volume disease and few organs affected was coined "oligometastases." It is hypothesized this state may be amenable to local therapy to improve outcomes. After long term follow up, patients with this limited metastatic progression appear to have relatively good outcomes, with some long-term survivors, after aggressive treatment with local therapy combined with systemic therapy. In the past 20 years since the conception of the oligometastatic hypothesis, there have been advances in surgical and radiation therapy techniques resulting in reduced toxicities. Additionally, developments in systemic therapy have prolonged survival for patients with metastatic disease. Herein we discuss the history and rationale for local treatment of oligometastases and delve into the implementation of stereotactic body radiotherapy (SBRT) to this evolving treatment paradigm.