Impact of loco-regional treatment on metastatic breast cancer outcome: a review

Metastatic breast cancer (MBC) at presentation (Stage IV) is a devastating diagnosis with a poor prognosis and a 5-year overall survival rate not exceeding 20%. The treatment is palliative, and its primary aim is to improve the patient's quality of life. In this context, the benefit of local therapy, considered to have no impact on survival, was to control the local evolution of the disease in order to limit the symptoms. Several publications have challenged this paradigm. These studies, either retrospective single-center or based on population cohorts, compared locoregional treatment to exclusive systemic therapy, which is the gold standard in this situation. The outcomes, marked by inherent biases as in all retrospective studies, mainly related to prognostic factors, albeit suggesting a strong and constant association between locoregional therapy and improvement of metastatic progression-free survival and overall survival. Furthermore, the advances made in the metastatic setting using innovative systemic therapies raise more than ever the interest in locoregional treatment. However, currently we have no data to better define subgroups of patients who would benefit from a strategy that include systematic local therapy. Thus, the important ongoing randomized trials may not only answer some of these issues, but will probably change the practice for many patients with MBC at diagnosis. In this review we will focus on the biologic hypotheses that support the importance of local therapy for MBC patients, review data published in this issue and summarize the ingoing trials.