Triple-negative breast cancer and radiation therapy.

Background: This study aimed to review specific indications of radiation therapy for triple-negative breast cancer (TNBC), and to introduce the hypothesis of TNBC as an independent predictor for postmastectomy radiation therapy (PMRT). Materials and methods: Two reviewers independently searched two electronic databases (Pubmed and Embase), with the inclusion dates of January 2000 to December 2021, for the following terms: "mastectomy" or "breast conserving surgery" or "lumpectomy", and "radiation" or "radiotherapy", and "triple negative" and "recurrence". All evidence was explored by two reviewers, then organized into a narrative review considering grades of recommendation. Results: Patients with TNBC are candidates for breast conserving surgery (grade of recommendation B). Postoperative whole-breast irradiation must be offered following breast conserving surgery (grade of recommendation A). Do not omit postoperative radiation therapy in older patients with TNBC (grade of recommendation B). Do not use partial-breast irradiation in patients with TNBC (grade of recommendation B). Postmastectomy radiation therapy should be offered for women with T3-T4 or node-positive TNBC, for any number of positive nodes (grade of recommendation A). Radiation therapy following mastectomy might also benefit patients with T1-T2 node-negative TNBC (grade of recommendation B). For patients treated with neoadjuvant systemic therapy, radiation therapy indication is based on pretreatment features. Retrospective studies suggest that residual TNBC is sensitive to radiation therapy to optimize locoregional control (grade of recommendation C). Conclusions: Postoperative radiation therapy should be offered for most patients with TNBC. Upcoming studies, preferably prospective randomized trials, should evaluate the indications of radiation therapy, especially in the context of novel systemic treatments.