Dear Editor,

I want to congratulate Hennigs and their colleagues for their article [1] in which they investigated which patients with sentinel lymph node (SLNs)-positive breast cancer after breast conservation still received completion axillary lymph node dissection (cALND) in routine clinical practice. They reported that fewer removed SLNs, two tumour-affected SLNs, younger age, lower annual case volume per hospital, higher tumour grade, and lymphovascular invasion were associated with cALND. However, the authors did not take extranodular extension (ENE) of positive SLN into consideration as a variable for further cALND. One study evaluated he prognostic role of ENE in SLN-positive breast cancer patients in terms of overall and disease-free survival by conducting a systematic review and meta-analysis. They globally included 624 patients (163 ENE+ and 461 ENE−) with a median follow-up of 58 months. ENE was associated with a higher risk of both mortality and recurrence of disease [2]. In conclusion, ENE in SLN-positive breast cancer seems to be strongly associated with a poorer prognosis in breast cancer and might predict further initiation of cALND.