Axillary lymph node dissection can be omitted in patients with limited clinically node-positive breast cancer: a National Cancer Database analysis.

Background: De-escalation of axillary surgery in breast cancer has progressively taken place when appropriate. Data supporting surgical de-escalation in patients with clinically node-positive (cN+) disease remains scarce. Here, survival among patients with cN+ T1-2 tumours undergoing sentinel lymph node biopsy (SLNB) and regional nodal irradiation (RNI) was investigated and compared with that among patients undergoing axillary lymph node dissection (ALND) with or without RNI.

Methods: The National Cancer Data Base was used to identify three groups of patients with cN+ tumours according to axillary management among those treated between 2010 and 2016: patients who underwent SLNB and RNI (cN+ SLNB/RNI group); those who had ALND and RNI (cN+ ALND/RNI group); and those who had ALND alone (cN+ ALND/no RNI group). Patients who underwent neoadjuvant chemotherapy, and those who had stage IV breast cancer or pN2-3 disease were excluded.

Results: A total of 12 560 patients met the inclusion criteria: 3030 in the cN+ SLNB/RNI, 5446 in the cN+ ALND/RNI, and 4084 in the cN+ ALND/no RNI group. The sizes of cN + SLNB/RNI and cN+ ALND/RNI groups increased over the study interval, whereas the cN+ ALND/no RNI group decreased in size (P < 0.001). There was a median of one positive node in the cN+ SLNB/RNI group and two nodes in the cN+ ALND/RNI and cN+ ALND/no RNI groups. The median number of nodes examined was three, 14, and 14, respectively (P < 0.001). Median follow-up was 57.9 (range 0.8-114) months. The overall survival rate was 97, 97, and 92 per cent respectively at two years, and 88, 86, and 78 per cent at five years (P < 0.001).

Conclusion: Patients with limited cN+ T1-2 breast cancer undergoing upfront SLNB and RNI have favourable survival outcomes that are not inferior to those of patients undergoing ALND with or without RNI. Prospective studies are warranted to assess locoregional control and long-term outcomes.