Tumor Size and Lobular Histology Predict for Higher Pathologic Nodal Stage Regardless of Clinical Presentation of Nodal Disease in Patients With Breast Cancer

Abstract Purpose: Omission of axillary lymph node dissection (ALND) is considered for patients with sentinel lymph node-positive (SLN+) breast cancer, but ALND remains the standard of care for clinically node-positive (cN+) patients treated with surgery first. Here, we evaluate differences in patient and tumor characteristics and pathologic nodal stage in patients with positive lymph nodes who underwent ALND. Methods: Retrospective chart review from 2010-2019 identified three groups of patients who underwent ALND for positive nodes: SLN+ (positive node identified at SLN biopsy), cNUS (abnormal preoperative US and biopsy), and cNpalp (palpable adenopathy). Patients who received neoadjuvant chemotherapy or presented with axillary recurrence were excluded. Results: Of 218 patients, 107 were SLN+, 43 were cNUS, and 68 were cNpalp. SLN+ patients compared with cNpalp were more likely to be younger (56 vs 64,p<.01), pre-menopausal (39%vs15%,p<.01), and white (62%vs37%,p<.01) with more tumors that were progesterone receptor-positive (6%vs21%,p=.02), low grade (35%vs6%,p<.01) and without lymphovascular invasion (11%vs27%,p=.02). SLN+ patients had more pN1 disease than cNUS and cNpalp (67.3% vs 39.5% vs 42.6%, p<.01). Greater tumor size and lobular histology were significantly associated with higher nodal stage in univariable regression analysis of SLN+ patients as well as a pooled analysis of the three clinical groups.Conclusion: Patient and tumor characteristics differ on either end of the nodal spectrum, with cNpalp patients having higher risk features than SLN+ patients. These higher risk features have historically resulted in ALND for patients with clinically positive nodes. However, only tumor size and histology are associated with higher pathologic nodal stage.