Retrospective study of outcomes with or without ALND in breast cancer with residual micrometastases after neoadjuvant chemotherapy

Despite the paucity of outcome data, axillary lymph node dissection (ALND) is increasingly being omitted in patients with with positive sentinel nodes after neoadjuvant chemotherapy, particularly in those with low-volume residual disease. The multinational retrospective OPBC-07/microNAC cohort study recruited 1585 patients with residual micrometastases in the sentinal lymph nodes (ypN1mi) after neoadjuvant chemotherapy and surgery. Among these patients, 804 (50.7%) underwent ALND, and 781 (49.3%) did not; 1267 (79.9%) received nodal radiotherapy. The median duration of follow-up was 3.1 years (IQR 1.8-5.2). The 3-year rate of any axillary recurrence (isolated or combined with local or distant recurrence) was 2.0% (95% CI 1.3-2.9), with no statistical difference identified by the extent of axillary surgery. However, patients with triple-negative breast cancer who did not receive ALND had significantly higher rates of axillary recurrens than TNBC patients treated with ALND (8.7% versus 2.4%; p=0.018). The authors conclude that overall these results do not support ALND for all patients with ypN1mi on sentinel lymph node biopsy treated with nodal radiotherapy, however, tumor biology should be taken into account when considering ALND omission.