51 Metastasis-Directed Therapy and Local-Regional Therapy for Patients With Metastatic Breast Cancer: Who, What, Where, and When?

Background

Women with metastatic breast cancer form a very heterogeneous population. Current breast cancer detection and systemic treatment options have resulted in longer survival for MBC patients of all molecular subtypes. The optimal treatment regarding the use of metastasis-directed therapy (MDT) and local-regional therapy for patients with asymptomatic lesions remains controversial.

Objective

The spectrum of metastatic breast cancer includes patients with different presentations, tumor burdens, biologic characteristics, and exposure to and responses to systemic therapy. Oligometastatic and oligoprogressive metastatic breast cancers have been identified as unique intermediate disease states with superior prognoses compared to most patients with metastatic breast cancer. Using MDT for such patients may potentially lead to long-term local disease control. This in turn could improve progression-free survival (PFS), overall survival (OS), and quality of life (QOL). We will summarize the existing literature on this subject and describe our views of when radiation therapy may be of benefit.

Materials and Methods

First, we define the spectrum of oligometastatic disease distinguishing between synchronous (de novo) and metachronous. Second, we report on current ablative radiation therapy practice patterns by reviewing current clinical guidelines available and noting nuances of each guideline. Third, we provide an overview of pertinent clinical trials, discussions, and considerations as it pertains to specific individual trials such as SABR-COMET, BR002, CURB, AVATAR, EXTEND, and RADIANT. Fourth, we review available literature for local regional therapy for patients with stage IV de novo breast cancer, including EA2108, Tata Memorial, MF0701, and ABCSG-28 POSYTIVE. Finally, we review the special scenarios that have shown promise for exceptional clinical scenarios.

Results

See Table.

Conclusion

Putting it all together, this is a review in summary targeting treatment for patients with oligometastatic/oligoprogressive breast cancer. Current randomized data do not support the routine use of targeted treatment for patients with oligometastatic/oligoprogressive breast cancer. Locoregional therapy for stage IV de novo breast cancer does not improve OS or QOL. However, special scenarios such as young patients with bone-only metastasis, specifically patients with sternal/mediastinal metastasis, have improved outcome with MDT. Trimodality therapy has also shown promise in improving OS. Results may reflect an insufficient ability to stratify patients according to characteristics that may correlate with a benefit from MDT. Future studies classifying patients by molecular subtype and innovative imaging techniques may assist multidisciplinary oncology teams to better tailor MDT for patients with oligometastatic and/or oligoprogressive breast cancer.