Stereotactic radiotherapy in metastatic breast cancer

The treatment of metastatic breast cancer is largely focused on systemic therapy. However, over the past decades, there has been growing interest in the use of metastasis-directed therapy in selected cases presenting with an oligometastatic phenotype, i.e. low disease burden with a more indolent biology. Identification of the oligometastatic breast cancer population has, so far, proven elusive. Stereotactic radiotherapy offers an effective, non-invasive approach to ablate metastatic disease both in the brain and in extra-cranial settings. The advent of advanced imaging techniques for target definition, along with the ability to achieve highly conformal dose deposition with steep dose fall-off, enable safe implementation of extreme hypofractionated and single fraction regimens with ablative intent. There is growing evidence that radiation-based treatments are more cost-effective when compared to other ablative modalities. This article provides preliminary evidence that metastasis-direct ablation, with advanced radiotherapy techniques, may play an important role in the management of metastatic breast cancer patients, potentially improving clinical outcomes with minimal toxicity. However, prospective randomized controlled trials are needed to further the understanding of the interaction between systemic therapy and ablative irradiation. Additionally, research in genomic and molecular profiling is needed to characterize metastatic breast cancer patients who will most likely benefit from such combined treatment approaches.