Tailored axillary surgery to omit axillary lymph node dissection independently from the use of neoadjuvant chemotherapy in patients with clinically node-positive breast cancer: Pre-specified subproject within TAXIS (SAKK 23/16/IBCSG 57-18/ABCSG-53/GBG 101)

Abstract Introduction: We developed tailored axillary surgery (TAS) to selectively remove positive nodes and omit axillary lymph node dissection (ALND) in patients with clinically node-positive breast cancer irrespective of the use of neoadjuvant chemotherapy. In this study, we evaluate the performance of this novel surgical concept that tailors the extent of axillary surgery to the extent of axillary disease. Methods: A prospective study was pre-specified to assess the performance of TAS in the international multicenter phase-III TAXIS trial randomizing patients with clinically node-positive breast cancer to undergo ALND or axillary radiation after TAS. TAS consists of selective removal of all palpably suspicious findings and the SLNs followed by specimen radiography to document removal of the clip placed in the sampled node. Imaging-guided localization is encouraged to increase the chances of clip removal. Only patients with confirmed nodal disease at the time of surgery can be randomized in TAXIS; the first 200 randomized patients were analyzed together with the ones achieving nodal pCR in this study. ClinicalTrials.gov Identifier: NCT03513614. Results: A total of 296 patients with a median age of 56.5 years (range: 25-88 years) were included at 28 breast centers from four European countries, 125 (42.3%) of whom underwent NACT and 75 (25.3%) of whom had nodal pCR. Subtype was hormone receptor (HR) positive (+) and human epidermal growth factor receptor 2 (HER2) negative (-) in 194 (65.5%), HR+/HER2+ in 40 (13.5%), HR-/HER2+ in 17 (5.7%) and HR-/HER2- in 39 (13.2%) patients. Breast-conserving surgery was performed in 178 patients (60%) and mastectomy in 117 (40%). Imaging-guided localization was attempted in 258 patients (87.2%) and was successful in 243 (82.1%). TAS removed a median of two (interquartile range [IQR] 0-3) palpably suspicious lesions and two (IQR 1-3) SLNs, thereby successfully removing the clip in 279 (94.3%) patients. There were no significant differences by use of imaging-guided localization (94.6% with vs 92.1% without, p=0.47) or type of clip (p=0.19), but a trend toward lower rate of clip removal after NACT (91.2% with vs 96.5% without NACT, p=0.075). Palpable disease was left behind after TAS in two (2.1%) patients and no SLN was detected in three (3.1%). In the 200 randomized patients with confirmed nodal disease at the time of surgery, lymph node metastases were palpable at the time of initial diagnosis in 102 (51%) patients and detectable only by imaging in 98 (49%). The median number of lymph nodes removed by TAS was four (IQR 2-8), two (IQR 1-4) of which were positive. Completion ALND following TAS removed additional positive nodes in 71 of 100 (71%) patients in the control group (20% with one additional node, 9% with 2, 8% with 3, 6% with 4, and 28% with >4). The median number of additional lymph nodes removed by ALND was 14 (IQR 10-18), two (IQR 0-6) of which were positive. Of the 200 randomized patients, one in the TAS group received a radiotherapy boost and one in the ALND group returned to the operating room for residual suspicious findings on imaging. Discussion: The present results suggest that TAS has the potential to become the new axillary surgery standard in patients with clinically node-positive breast cancer. TAS was successfully performed in the vast majority of patients, with no further improvement by imaging-guided localization, which makes the procedure feasible at most breast centers. TAS selectively removed positive lymph nodes and was much less radical than ALND, but ALND removed additional positive nodes in more than two thirds of patients. Disease-free survival and quality of life will be assessed in the randomized trial. Citation Format: Walter Paul Weber, Guido Henke, Stefanie Hayoz, Karin Ribi, Stefanie Seiler, Charlotte Maddox, Thomas Ruhstaller, Daniel Rudolf Zwahlen, Simone Muenst, Markus Ackerknecht, Florian Fitzal, Mihály Újhelyi, Christian Kurzeder, Loïc Lelièvre, Christoph Tausch, Daniel Egle, Jörg Heil, Zoltan Matrai, Michael Knauer. Tailored axillary surgery to omit axillary lymph node dissection independently from the use of neoadjuvant chemotherapy in patients with clinically node-positive breast cancer: Pre-specified subproject within TAXIS (SAKK 23/16 / IBCSG 57-18 / ABCSG-53 / GBG 101) [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PD4-04.