The Potential Role of Radiation Therapy to the Primary Site of Disease in Stage IV Breast Cancer Presenting With Synchronous Metastasis

Abstract

Introduction The benefit of local therapy in the form of surgery or radiation therapy to the chest wall or intact breast remains unproven in patients diagnosed with stage IV breast cancer. Traditional therapy for these patients consisted of primary systemic therapy, with surgery or radiation therapy reserved for palliation of symptomatic local disease only after control of systemic disease. Stage IV breast cancer patients constitute a heterogeneous population with regard to molecular subtype, age, overall disease burden, visceral organ involvement, and treatment response to endocrine therapy, biologic agents, or chemotherapy, all of which contribute to prognosis. With the advent of new therapeutic strategies, the 3-year survival rate increased from 27% to 44% in a French multicenter study. With the increasing efficacy of systemic therapy, a subgroup of stage IV patients may achieve a complete clinical and radiologic response. Emerging data, mostly examining the efficacy of surgery, suggest an overall survival (OS) advantage with aggressive management of the primary site of disease in stage IV breast cancer. Similar findings to support surgical resection in select stage IV patients have also been reproduced with the database of the Surveillance, Epidemiology, and End Results (SEER) Program of the National Cancer Institute and institutional observational protocols. The benefit of radiation therapy to the primary tumor, either following or replacing surgery, in this cohort of patients remains unknown. Our clinical commentary visits the role of locoregional therapy of the primary tumor in patients with metastatic disease at diagnosis. Further, we explore the existing data and the potential role of radiation in this setting.