Axillary management still needed for patients with sentinel node micrometastases

More attention has been paid to the axillary management over the past 50 years, and clinical practice has been changed as results of the random controlled trials. The American College of Surgeons Oncology Group Z0011 and International Breast Cancer Study Group (IBCSG) 23-01 trials provided high-level evidence to support the omission of axillary lymph nodes dissection (ALND) in sentinel lymph node (SLN)-positive patients receiving breast-conserving surgery (BCS) and adjuvant systemic treatment. In patients treated with BCS, whole breast irradiation (WBI) with tangential fields could lead to substantial axillary irradiation and control the residual tumor burden in axilla, whereas (intraoperative) partial breast irradiation has no therapeutic effect on these residual axillary metastases. In the observation group of the IBCSG 23-01 trial, 425 patients received BCS and 80 (18.8%) of them just underwent intra-operative radiotherapy. While the 10-year axillary recurrence rate was acceptable low (1.7%, 8/467) in the no ALND group, it was 4.5% (6/134) in patients without axillary management, which was significantly higher than that of 0.6% (2/333) in patients with axillary management (P=0.0024). Should we accept an axillary recurrence rate as high as 4.5% in patients with only SLNs micrometastases? What is the best way to control the residual tumor burden in the axilla and decrease the recurrence rate if there is no ALND? The evidence showed that both WBI after BCS (Z0011, AATRM [Agència d’Avaluació de Tecnologia i Recerca Mèdiques]) and axillary regional nodal irradiation after mastectomy/BCS OTOASOR (Optimal Treatment Of the Axilla - Surgery Or Radiotherapy), AMAROS (After Mapping of the Axilla: Radiotherapy Or Surgery) could control the regional residual tumor burden when the SLN is positive and an ALND is omitted. In the modern era, systemic therapy could further decrease the risk of local/regional recurrences. After the subanalysis of the POSNOC (POsitive Sentinel NOde: adjuvant therapy alone versus adjuvant therapy plus Clearance or axillary radiotherapy), SERC (Sentinelle Envahiet Randomisation du Curage), and Dutch BOOG (BOrstkanker Onderzoek Groep) trials, a prediction model might be established to identify those patients who could beneft from no axillary management as a guide to clinical practice. At present, axillary management should still be required for patients with SLN micrometastases.