Judy C. Boughey

As axillary surgery de-escalates and neoadjuvant systemic therapy (NST) improves, we sought to evaluate changes in axillary surgery and impact on overall survival (OS) in occult breast cancer with axillary metastasis. Using the National Cancer Database, we identified patients with cT0N+ breast cancer who underwent axillary surgery between 2012 and 2023. Lymph node surgery trends were assessed using Cochran-Armitage trends tests and the Kaplan-Meier method evaluated OS. We identified 1817 patients with cT0N+ breast cancer (75% had surgery first and 25% received NST). NST use significantly increased over time. Patients undergoing upfront surgery primarily underwent ALND (94% ALND, 6% SLN only); however, ALND decreased from 96 to 82% (2012-2023), p < 0.001. Three-year OS was similar between SLN and ALND in this cohort (96% versus 93%, p = 0.12). In patients who received NST, ALND rate was lower and had a greater decrease from 97 to 70% (2012-2023), p < 0.001, especially 2017 onwards. Of ypN0 patients, 26.0% underwent SLN only with highest rates in the most recent year (2023: 44.4%), whereas 9.6% of patients with ypN+ had SLN only. OS was similar between SLN only and ALND for patients with ypN0 disease (3 year Kaplan-Meier estimates 100% versus 96%, p = 0.77) as well as ypN+ disease (93 versus 91%, p = 0.43). For patients with occult breast cancer with axillary metastases, the extent of axillary surgery is deescalating, with the greatest decrease in those receiving NST. Early survival data suggests a lack of survival benefit with ALND compared with SLN surgery with appropriate patient selection.