Oligometastatic Breast Cancer

Oligometastatic breast cancer is typically defined as the presence of 1-5 metastases and represents an intermediate state between locally advanced and widely metastatic disease. Oligometastatic cancer appears have a molecular signature that is distinct from widely metastatic disease and is associated with a superior prognosis. Due to its more limited capacity for widespread progression, oligometastatic disease could potentially benefit from aggressive ablative therapy to known sites of disease. The phase II SABR-COMET trial enrolled patients with oligometastatic disease of multiple histologies and randomized them to HIGRT vs. standard of care, finding a notable survival advantage in favor of HIGRT. There are many ongoing trials exploring the role of HIGRT for the treatment of oligometastatic breast cancer. Future studies may identify optimal candidates for ablative therapy by molecular signature; current clinically-based selection criteria include longer disease-free interval from diagnosis to metastasis (>2 years), fewer metastases, and fewer involved organs.