Impact of axillary surgery on survival in de novo metastatic breast cancer with primary tumor resection.

PURPOSE: The role of axillary surgery in patients with de novo metastatic breast cancer (dnMBC) undergoing primary site surgery is unclear. We evaluated patterns of axillary management and associations with overall survival (OS) in this population.

METHODS

We used the National Cancer Database (2012-2020) to identify patients with dnMBC. Patients were grouped by receipt of breast surgery and axillary surgery (none, sentinel lymph node biopsy [SLNB] or axillary lymph node dissection [ALND]). Multivariable Cox proportional hazards models assessed factors associated with axillary surgery and OS.

RESULTS

Among 39,946 eligible patients, 7,808 (19.5%) underwent surgery of the primary site, of whom 79.8% underwent axillary surgery (79.5% ALND, 20.4% SLNB). Compared with no axillary surgery, those who underwent axillary surgery had more favorable clinicodemographic characteristics (younger, fewer comorbidities, lower T stage, bone-only metastases). In patients with clinically node-negative disease, 41.6% had pathologically negative nodes, with higher rates among those with HR+/HER- disease and those who did not have systemic therapy prior to surgery. On multivariable analysis, axillary surgery was independently associated with improved OS (HR 0.70; 95% CI 0.63-0.78; p<0.001).

CONCLUSION

Among patients with dnMBC undergoing primary site surgery, axillary surgery was associated with improved survival in this retrospective analysis, though the effect is likely influenced by selection bias. Until prospective data define which subgroups may benefit, axillary surgery should be considered selectively, with SLNB preferred over ALND for patients without palpable adenopathy to minimize morbidity. Multidisciplinary evaluation remains essential to tailor surgical decisions that balance survival, function, and quality of life.