Breast-Conserving Treatment in Patients with Triple-Negative Breast Cancer Subtype

Abstract

INTRODUCTION: It is well established that breast cancer (BC) is a heterogeneous disease, with different behaviour and sensitivity to the treatments in accordance with the distinct molecular subtypes. In the contemporary management of BC, several possibilities exist for local treatment. In the present study we attempted to determine whether patients with triple-negative BC can be safely treated by quadrantectomy and radiation therapy. METHOD: A total of 265 women with early infiltrating BC (T1-2) were treated by quadrantectomy, axillary dissection based on sentinel node status and external radiotherapy, from 2006 to 2011. All patients had a pretreatment magnetic resonance imaging and had surgical specimens assessed intraoperatively to guarantee clear margins. Forty-eight cases were excluded because the absence of FISH test in HER-2 ++ or unknown hormonal receptors. No patients received neoadjuvant therapy. Adjuvant systemic therapy was administered according to the institutional guidelines. The patients were divided in two groups: 1. Triple-negative tumors (negative immunohistochemical staining for estrogen receptor, progesterone receptor and oncogene HER-2); and 2. Non-triple- negative tumors. The cohort used for this study was derived from the archival paraffin-embedded samples collected at Laboratorio Diagnostika. Local relapse (LR) was defined as disease recurrence within the ipsilateral breast, discovered by physical examination or imaging diagnosis during the follow-up. RESULTS: Amoung the 217 evaluable cases, 21 (9. 6%) were classified as triple- negative (group 1) and 196 (90. 3%) as non-triple-negative (group 2). During the follow-up 9 patients had LR (4. 1%): 6 invasive lesions and 3 ductal carcinoma in situ. All of the LR occurred among the patients with non-triple-negative tumors. So, in the group 2 there were 9 cases of LR (4.5%), while in the group 1 there were no cases of LR. CONCLUSION: This study suggests that patients with triple-negative BC, submitted to preoperative magnetic resonance imaging and intraoperative evaluation of surgical margins, can be safely treated by quadrantectomy and radiotherapy with optimal local control.