Abstract P3-03-30: Validity and safety of omission of axillary lymph node dissection among sentinel lymph node-positive breast cancer patients treated with mastectomy

Abstract

Background:American College of Surgeons Oncology Group Z0011 trial showed that axillary lymph node dissection (ALND) had no impact on recurrence and survival in patients with positive sentinel lymph node (SLN) after breast-conserving surgery. However, it is still unknown if the omission of ALND can be applicable to patients treated with mastectomy. The aim of this study wasto evaluate whether ALND could be safely omitted for patients with SLN–positive breast cancer after mastectomy. Methods: From a prospective database of 296 patients with clinically node-negative breast cancer who underwent mastectomy and sentinel lymph node biopsy (SLNB) from March 2006 to December 2016, 81 patients who had positive SLNs were selected. Patient characteristics and prognosis were compared between SLN-positive patients with and without ALND. Patients treated with neoadjuvant chemotherapy were excluded from the analysis. Lymphatic mapping was performed using a combined method of blue dye and radioisotope. Results: The median age of entire patients was 57.0 (range: 32-85) years and the median tumor size was 2.5 (range: 0.6-7.9) cm. Of 81 patients, 23 (28.4%) patients omitted ALND. Patients with SLNB alone were more likely to have smaller SLN involvements (p<0.001): micrometastasis was identified in 13 (56.5%) patients in SLNB-alone group and 9 (15.5%) patients in ALND group. The number of positive SLN was comparable between SLNB-alone (median: 1.0, range: 1-6) and ALND groups (median: 1.0, range: 1-5) (p=0.063). There was no significant difference in characteristics including age, tumor size and tumor subtypes between the two groups. Post-mastectomy radiotherapy was performed in 5 (21.7%) patients with SLNB alone and 16 (27.6%) patients with ALND (p=0.588). The majority of patients with macrometastatic SLN received adjuvant chemotherapy in both groups (83.3% vs. 75.5%, p=0.562). Twenty (87.0%) and 51 (87.9%) patients received adjuvant endocrine therapy in SLNB-alone and ALND group, respectively (p=0.584). After a median follow-up of 54.7 months, no axillary recurrence was observed in both groups and 5-year disease-free survival was not significantly different between the two groups (75.0% vs. 88.8%, p=0.489). Lymphedema was observed significantly more often after ALND than after SLNB (22.4% vs. 4.3%, p=0.045). Conclusions: These data suggested that ALND could be safely omitted in SLN-positive breast cancer patients treated with mastectomy and appropriate systemic therapy. Citation Format: Matsumoto A, Umemoto Y, Jinno H. Validity and safety of omission of axillary lymph node dissection among sentinel lymph node-positive breast cancer patients treated with mastectomy [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P3-03-30.