Utility of axillary surgery in patients with de novo metastatic breast cancer undergoing surgery of the primary site.

Abstract

1086 Background: Approximately 6% of patients have de novo metastatic breast cancer (MBC) for whom surgery is reserved for special circumstances since it confers no survival benefit. The prospective studies evaluating surgery of the primary site in MBC recommended standard surgical management of the axilla. However, it is unclear whether axillary surgery is of any utility among these patients. We sought to evaluate the survival benefit of axillary surgery in MBC patients undergoing primary site surgery. Methods: From the National Cancer Database (2012-2020), we identified patients aged 18-79 with MBC undergoing surgery of the primary site and grouped patients according to axillary surgery performed: none, sentinel lymphadenectomy (SLNB), or axillary lymph node dissection (ALND) with or without SLNB. We performed a landmark analysis beginning 12 months after diagnosis to assess overall survival (OS) and used Cox regression to adjust for clinicodemographic characteristics. Results: We identified 7,808 patients, 20.2% of whom had no axillary surgery, 16.3% had SLNB, and 63.5% had ALND. Of the patients who had axillary surgery, 26.3% were pN0. Patients who had no axillary surgery, were older (mean 57.2 vs 60.3 years), more likely to have tumor histology other than ductal or lobular (8% vs. 4%), be cN0 (28% vs. 20%), less likely to have bone-only metastases (36% vs. 44%) and undergo breast-conserving surgery (49% vs. 24%) [all p<0.001]. The mean and median number of positive nodes was 1.3±2.3 in the SLNB, and 5.9±6.8 in the ALND group. 36-month adjusted survival estimates were 71.4%, 66.5%, and 58.0% for SLNB, ALND, and no axillary surgery groups, respectively. On univariate analysis and after adjusting for clinicodemographic features, both SLNB and ALND remained independently associated with improved OS when compared with no surgery (Table). Conclusions: As in prior retrospective analyses of surgery for the primary site, we found that the performance of axillary surgery in MBC patients was associated with improved OS. Selection bias is likely a contributing factor as surgeons are more likely to recommend axillary surgery for patients with a better functional status. Of concern is the number of MBC patients being exposed to the morbidity of ALND who are ultimately pN0, and thus derived no benefit. These findings highlight the need to carefully weigh the risks and benefits before performing axillary surgery. Prospective studies evaluating axillary surgery are needed to validate these results. [Table: see text]