Locoregional treatments for triple-negative breast cancer

The absence of drug-targetable receptors in triple-negative breast cancer (TNBC) makes the use of targeted systemic therapy inappropriate for this breast cancer subgroup. Although patients with TNBC show sensitivity to some chemotherapy regimens, in early-stage disease greater emphasis is placed on locoregional treatments, based on surgery and radiation therapy (RT). Ongoing improvements in both screening and surgical techniques have reduced the need for radical surgical intervention in all breast cancers, and breast-conserving surgery (BCS) followed by RT is now increasingly common for all tumour types. However, while evidence has clearly established the importance of post-surgical RT for favourable long-term outcomes in breast cancer, it is less well-established as to where and under which conditions more radical surgeries than BCS, such as modified radical mastectomy (MRM), may be indicated for TNBC. A high proportion of TNBC tumours are BRCA1-mutated and therefore patients with this type of tumour are at a potentially elevated risk of ipsilateral or contralateral recurrence. In addition, while some studies indicate that post-BCS locoregional TNBC relapse rates generally appear similar to other tumour types, some evidence suggests that distant relapse rates may be higher. There is evidence that some subtypes of TNBC may require MRM rather than BCS for optimal long-term outcomes. More research is needed to establish whether TNBC-specific approaches to locoregional treatment may be required.