Role of radiation therapy in triple negative breast cancer: current state and future directions—a narrative review

Objective: This article is a narrative review of published data regarding locoregional radiotherapy in triple negative breast cancer (TNBC) patients. Background: Patients with TNBC tend to recur earlier as compared to other subtypes. In addition, TNBC has been associated with distinct features such as young age, aggressive morphological features and worse outcomes that don’t always correlate with traditional prognostic features. Moreover, regional and distant recurrences seem to occur more frequently than non-TNBC patients. Locoregional radiotherapy plays an important role in the management of these patients. Current challenges focus on the development of strategies combining locoregional management and systemic treatments. Furthermore manipulation of the immune system with a combination or radio-immunotherapy is being explored in trials to improve outcomes in this subtype which lacks expression of other molecular targets. Methods: Using medical subject headings (MeSH) terms and text words related to ‘breast cancer’ ‘radiotherapy’ ‘triple negative’, PubMed and Medline (OVID) electronic databases were searched from 2009 till June 2020. Abstracts were reviewed and appropriate full-manuscripts retrieved. This search was complemented by the authors’ personal and institutional expertise. We looked into the timing and pattern of recurrences, role of radiotherapy following neoadjuvant chemotherapy and possible immune-radiotherapy combination mechanisms to guide future strategies. Conclusions: TNBC patients have a distinct recurrence pattern consisting in early recurrences, mainly regional nodal recurrences in the axilla and the supraclavicular region. Postmastectomy radiotherapy (PMRT) is of value in advanced disease, however it could be discussed in early stage disease in a patient presenting with multiple high risk factors of recurrence. Use of radiotherapy (RT) is strongly advocated after neoadjuvant treatments. Radio-immunotherapy should ideally be tested in the oligometastatic setting.