Size of extranodal extension on sentinel lymph node dissection in the American College of Surgeons Oncology Group Z0011 trial era

Abstract

IMPORTANCE: Based on the American College of Surgeons Oncology Group Z0011 trial exclusion criteria, patients with T1N0 or T2N0 breast cancer with 1 or 2 positive sentinel lymph nodes (SLNs) are recommendedto undergo axillary lymph node dissection if extranodal extension (ENE) is present. OBJECTIVE: To determine the effect of ENE size on residual axillary nodal burden, disease recurrence, and survival in patients meeting Z0011 criteria. DESIGN, SETTING, AND PARTICIPANTS: Retrospective cohort study between January 1, 2000, and December 31, 2012, at a single tertiary cancer center. Patients had T1 or T2 breast cancer with 1 or 2 positive SLNs. The ENE was classified as 2 mm or smaller or as larger than 2 mm. MAIN OUTCOMES AND MEASURES: Nodal burden, disease recurrence, and overall survival. RESULTS: Of 208 patients, 149 (71.6%) hadno ENE, 21 (10.1%) had ENE 2 mm or smaller, and 38 (18.3%) had ENE larger than 2 mm on SLN dissection. The median follow-up time was 60 months (range, 1-158 months). The mean (SD) total number of positive lymph nodes differed significantly for the group with no ENE (1.72 [1.39]) vs the group with ENE 2 mm or smaller (3.22 [2.09]; P