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Does addition of postmastectomy radiotherapy improve outcome of patients with pT1-2, N0 triple negative breast cancer as compared to breast conservation therapy?

Background: Triple-negative breast cancers (TNBCs) form a heterogeneous group of cancers typically exhibiting an aggressive behavior resulting in increased risk of locoregional relapse (LRR) and distant metastases. The effect of radiotherapy on LRR risk and overall survival (OS) in women treated with mastectomy alone for early-stage TNBC remains unclear. Aim: The aim of this study is to compare the locoregional recurrence rate, disease-free survival (DFS), and OS following breast conservation therapy (BCT) or modified radical mastectomy (MRM) alone in women with stage I and IIA TNBC and to assess the impact of tumor and treatment-related factors. Materials and Methods: Patients with early-stage (pT1-2, N0) TNBC-treated between January 1, 2010, and December 31, 2011, were identified from the hospital-based registry records. The mean age was 48 years. Forty-nine patients underwent BCT, and 121 underwent MRM. The majority of the patients in both groups had T2 and grade 3 disease. None of the patients had margin positive status after surgery. Five patients had lymphovascular invasion (LVI). Results: At a median follow-up of 50 months (range: 4–83 months), there was no locoregional recurrence (LRR) in either arm. Eight patients relapsed, six developed distant metastases, and one patient each had a new primary in the contralateral breast and ovary. Two patients died of disseminated cancer, one each in the BCT and MRM groups. The five-year DFS was 95.8% and 91.1% for the BCT group and MRM group, respectively, (P = 0.83). The corresponding 5-year OS was 98% and 97.5% (P = 0.527). There was no statistically significant difference in outcome based on age, grade, LVI, or margin status between both groups. Conclusion: This retrospective analysis identified no statistically significant difference in outcome regarding LRR, DFS, or OS in patients treated without adjuvant radiation for women with pT1-T2N0 TNBC who underwent MRM in comparison to BCT.