Extent of regional lymph node surgery and impact on outcomes in patients with early-stage breast cancer and limited axillary disease undergoing mastectomy

Purpose: Management of the axilla in patients with early-stage breast cancer (ESBC) has evolved. Recent trials support less extensive axillary surgery in patients undergoing mastectomy. We examine factors affecting regional lymph node (RLN) surgery and outcomes in patients with ESBC undergoing mastectomy. Methods: Women with clinical T1/2 N0 M0 invasive BC who underwent mastectomy with 1–2 positive nodes were selected from the National Cancer Database (2004–2015). Axillary surgery was defined by number of RLNs examined: 1–5 sentinel LN dissection (SLND), and ≥ 10 axillary LND (ALND). Binary logistic regression and survival analyses were performed to assess the association between axillary surgery and clinical characteristics, and overall survival (OS), respectively. Results: 34,243 patients were included: 13,821 SLND (40%) and 20,422 ALND (60%). SLND significantly increased from 21% (2004) to 45% (2015) (p <.001). Independent factors associated with SLND were treatment year, non-Academic centers, geographic region, tumor histology, and postmastectomy radiotherapy (PMRT). Multivariable survival analysis showed that ALND was associated with better OS (HR 0.78, 95% CI 0.72–0.83, p <.001) relative to SLND; however, there was no difference in patients with LN micrometastases treated without RT (HR 0.87, 95% CI 0.73–1.05, p =.153) or patients receiving PMRT (HR 0.92, 95% CI 0.76–1.13, p =.433). Conclusions: SLND has significantly increased in patients undergoing mastectomy with limited axillary disease and is influenced by patient, tumor, and treatment factors. Survival outcomes did not differ by axillary treatment for patients with LN micrometastases treated without RT or patients who received PMRT. SLND may be considered in select patients with ESBC and limited axillary disease undergoing mastectomy.