Abstract
BACKGROUND: Strategies to reduce the likelihood of axillary lymph node dissection (ALND) include application of Z0011 or use of neoadjuvant chemotherapy (NAC). Indications for ALND differ by treatment plan, and nodal pathologic complete response rates after NAC vary by tumor subtype. This study compared ALND rates for cT1-2N0 tumors treated with upfront surgery versus those treated with NAC. METHODS: The ALND rates for cT1-2N0 breast cancer patients were compared by tumor subtype among women undergoing upfront surgery to NAC. Multivariable analysis with control for age, cT stage, and lymphovascular invasion, and stratification by subtype was performed. RESULTS: The study identified 1944 cancers in 1907 women who underwent sentinel lymph node (SLN) biopsy with or without ALND (669 upfront breast-conserving surgeries [BCSs], 1004 upfront mastectomies, 271 NACs). Compared with the NAC group, the ALND rates in the BCS group were lower for estrogen receptor (ER), progesterone receptor-positive (PR(+)), human epidermal growth factor 2-negative (HER2(-)) tumors (15 vs 34%; p < 0.001). The ALND rates in the upfront mastectomy group were higher than in the NAC group for HER2(+) or TN tumors. In the multivariable analysis, receipt of NAC compared with upfront BCS remained significantly associated with higher odds of ALND in the ER/PR(+) HER2(-) subtype (hazard ratio [HR], 3.35; p < 0.001), whereas NAC versus upfront mastectomy remained significantly associated with lower odds of ALND in the HER2(+) and TN subtypes (HR for HER2(+), 0.19, p < 0.001; HR for TN, 0.25, p = 0.007). CONCLUSION: The study showed that ALND rates differ according to surgery type and tumor subtype secondary to differing ALND indications and nodal response to NAC. These factors can be used to personalize treatment planning to minimize ALND risk for patients with early-stage breast cancer.