Abstract RF2-07: Nodal disease burden in patients with clinically node-positive breast cancer undergoing tailored axillary surgery with or without axillary dissection in the neoadjuvant and upfront surgery setting: pre-planned TAXIS study (OPBC-03, SAKK 23/16, IBCSG 57-18, ABCSG-53, GBG 101)

Abstract Introduction: The safety of omitting axillary dissection (ALND) in patients with clinically node-positive breast cancer (cN+ BC) may depend on the nodal disease burden left behind in the axilla. This study aimed to evaluate nodal disease volume, quantify nodal understaging without ALND, and identify factors associated with additional nodal disease at ALND in these patients. Methods: The international phase-III TAXIS trial (NCT03513614) randomized patients with cN+ stage II-III BC to ALND or axillary radiotherapy (ART) following tailored axillary surgery (TAS). Nodal disease was detected by imaging or palpation at initial diagnosis. TAS removed sentinel, biopsied, and palpably suspicious nodes. Patients had upfront surgery or residual nodal disease after neoadjuvant chemotherapy (NACT). 1500 patients were randomized from 08/2018 to 08/2025.…