Axillary Surgery Omission Versus Sentinel Lymph Node Biopsy Versus Axillary Lymph Node Dissection in Early Breast...

Randomized trials support omission of selected axillary procedures in carefully defined early breast cancer populations. Whether these trial findings translate to broader real-world practice remains uncertain, particularly among patients who do not undergo any axillary surgery.

We analyzed women aged 18-85 y with surgically treated T1/T2N0M0 invasive breast cancer in the Surveillance, Epidemiology, and End Results database from 2018 to 2020. Patients were classified according to the number of lymph nodes examined as no axillary surgery (NAS; 0 nodes), sentinel lymph node biopsy (SLNB; 1-5 nodes), or axillary lymph node dissection (ALND; ≥10 nodes); patients with 6-9 nodes examined were excluded to reduce exposure misclassification. OS and CSS were evaluated using Kaplan-Meier analysis, multivariable Cox regression, matched-intersection propensity score strategy, IPTW, subgroup analyses, and sensitivity analyses. A postoperative CSS nomogram was developed among patients who had undergone NAS.

Among 50,367 patients, 2970 (5.9%) underwent NAS, 46,471 (92.3%) underwent SLNB, and 926 (1.8%) underwent ALND. After matched-intersection propensity score adjustment (746 patients per group), SLNB and ALND were associated with better OS and CSS than NAS. T stage modified the association with CSS (interaction P = 0.044), with the apparent disadvantage of NAS most evident among patients with T2 tumors. Additional sensitivity analyses restricted to hormone receptor-positive/HER2-negative disease and excluding patients diagnosed in 2020 produced directionally consistent findings. In the NAS cohort, 64 cancer-specific deaths occurred; the exploratory postoperative CSS nomogram incorporated T stage, PR status, and radiotherapy and showed a bootstrap-corrected C index of 0.808.

In this population-based retrospective analysis, NAS was associated with worse survival than SLNB or ALND, particularly among patients with T2 tumors. These findings are hypothesis-generating and should not be interpreted as evidence of a causal survival benefit from axillary surgery. The postoperative nomogram may assist exploratory risk stratification after NAS, but external validation and longer follow-up are required.