Abstract
BACKGROUND: The American College of Surgeons Oncology Group Z0011 trial demonstrated the safety of omitting axillary lymph node dissection (ALND) for women with fewer than three positive sentinel lymph nodes (SLNs) who are undergoing breast-conservation therapy (BCT). Because most of the women were postmenopausal with estrogen receptor (ER) positive cancers, applicability of ALND for younger patients and those with triple-negative (TN) or human epidermal growth factor receptor 2 (HER2) overexpressing (HER2+) tumors remains controversial. METHODS: From August 2010 to December 2015, patients undergoing BCT for cT1-2N0 disease and found to have positive SLNs were prospectively followed. Axillary lymph node dissection was indicated for more than two positive SLNs or gross extracapsular extension. Clinicopathologic characteristics, axillary surgery, nodal burden, and outcomes were compared between the high-risk patients (TN, HER2+, or age <50 years) and the remaining patients, termed average risk patients. RESULTS: Among 701 consecutive patients, 242 (35 %) were high risk: 31 (13 %) with TN, 48 (20 %) with HER2+, 130 (54 %) with age less than 50 years, and 33 (14 %) with more than one high-risk feature. The remaining 459 patients (65 %) were average risk. The high-risk patients were younger, had higher-grade tumors (p < 0.0001), and more often had abnormal nodes imaged (p = 0.02). In this study, SLNB alone was performed for 85 % high-risk versus 82 % average-risk cases (p = 0.39). A median of four versus three SLNs were excised (p = 0.04), and both groups had a median of one positive SLN. Additional positive nodes at ALND were found in 62 % high-risk patients versus 65 % average-risk patients (p = 0.8), with a median of three positive nodes in both groups. During a median follow-up period of 31 months, no patients experienced isolated axillary recurrences. CONCLUSIONS: Axillary lymph node dissection was no more likely to be indicated for high-risk patients. For patients undergoing ALND, the nodal burden was similar. For patients otherwise meeting the American College of Surgeons Oncology Group (ACOSOG) Z0011 clinical eligibility criteria, ALND is not indicated on the basis of age or subtype.