Abstract P4-02-07: Validity of omission of axillary lymph node dissection after neoadjuvant chemotherapy for node-positive primary breast cancer
Authors: Akiko Matsumoto, Yasuko Umemoto, Daisuke Tsukahara, Hiromitsu Jinno
Journal: Cancer Research (2020)

Abstract Background: Anthracycline and taxane-based neoadjuvant chemotherapy (NAC) has been shown to downstage axillary lymph nodes in approximately 40% of patients. However, the feasibility of sentinel lymph node biopsy (SLNB) following NAC for initially node-positive patients is unclear because of high false-negative rates reported in previous trials. The aim of this study was to evaluate whether axillary lymph node dissection (ALND) could be safely omitted for patients with clinically node-positive breast cancer treated with NAC. Patients and methods: We identified 128 patients with clinically node-positive breast cancer who received NAC from March 2006 to March 2017. A correlation between axillary pathologic response and clinicopathological factors was analyzed. Preoperative clinical assessment of lymph-node status was performed by palpation and diagnostic imaging such as ultrasound and MRI. Lymphatic mapping was performed using a combined method of blue dye and radioisotope. Results: The median age was 56.5 (range: 29-79) years and the mean tumor size was 3.6 ± 2.37cm. Of 128 patients, 72 (56.2%) patients had luminal, 32 (31.3%) had HER2-positive, and 24 (18.8%) had triple-negative disease. Sequential anthracycline and taxane were administered for 115 (89.8%) patients, and 25 (78.1%) patients with HER2-positive disease received concomitant trastuzumab preoperatively. Overall, 53 (41.4%) patients achieved axillary pathologic complete response (ypN0). The ypN0 status was significantly correlated with clinical complete response (cCR) in breast (67.9%, p=0.004), ER-negative disease (59.5%, p=0.004) and HER2-positive disease (56.3%, p=0.049). Multivariate analysis demonstrated that cCR in breast (p=0.015) and ER negativity (p=0.006) were significant predictive factors for ypN0. In 14 ER-negative patients achieving cCR in breast, ypN0 was found in 12 (85.7%) patients. Among 85 patients who converted to clinically node-negative, ALND was omitted in 16 patients (18.8%) after SLNB. Of these 16 patients, irradiation to whole-breast and axilla was performed in 14 (87.5%) and 5 (31.3%) patients, respectively. After a median follow-up of 53.2 months, no axillary recurrence was observed in entire patients and 5-year disease-free survival was not significantly different between patients with or without ALND (85.5% vs. 87.5%, p=0.965). Conclusions: As ER-negativity and cCR were correlated with high eradication rate of initially positive lymph nodes, these patients might be good candidates of omission of ALND after NAC. Citation Format: Akiko Matsumoto, Yasuko Umemoto, Daisuke Tsukahara, Hiromitsu Jinno. Validity of omission of axillary lymph node dissection after neoadjuvant chemotherapy for node-positive primary breast cancer [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P4-02-07.