SLNB has become the standard approach for axillary staging in patients with breast cancer worldwide. This procedure yields the same staging power as axillary lymph node dissection with less complications and better quality of life [30
]. This less invasive procedure is possible for several reasons: i) Removal of lymph nodes is performed for staging purposes and not with curative intent [31
], therefore, the well-known risk of having a false-negative result can be accepted and comprehended; ii) even if the false-negative risk can be generally quantified in about 6%, the occurrence of overt axillary lymph node metastases after a negative SLNB has been shown to be lower than expected, being 0.9% after a median follow-up of 48 months in a cohort of 3,548 patients [6
]; iii) to date, the impact of the prognostic information of axillary lymph node status in the decision-making process is less important than in the past as the adjuvant treatment is becoming increasingly tailored towards the biological features of the disease rather than the risk of recurrence.
The introduction of SLNB represented a revolution and one of the latest innovations on the path of minimizing the surgical approach to breast cancer patients. As it is a functional concept rather than an anatomical entity, SLNB can be applied also to special clinical scenarios in which lymphatic drainage might be different than under physiologic conditions.
As previously mentioned, we also have to bear in mind that lymph node surgery is not curative in itself and has the aim of improving regional control of the disease and of achieving prognostic information. From this standpoint, the future evolution of lymph node surgery will probably be in the direction of further reduction since medical treatment will be more tailored in accordance with tumor biology rather than recurrence risk, especially when better diagnostic tools become available.
A recent publication with data taken from the first 566 patients with positive SEN of the AMAROS trial [34
] did not find any significant differences in terms of administration of adjuvant systemic therapy. The authors concluded that the absence of knowledge regarding the extent of nodal involvement in the axillary radiation therapy (ART) arm appeared to have no major impact on the administration of adjuvant treatment. The findings of the American College of Surgeons Oncology Group Z0011 trial push ahead the field of controversy [34
]. In fact, in this trial, which compared axillary clearance with observation in patients with SLN involvement, outcome appeared identical in the 2 groups in terms of overall survival, disease-free survival, and axillary recurrence. Those arguments are in favor of minimizing axillary surgery.
Based on all these considerations, we do not believe that it is necessary to validate SLNB in advance in every special clinical setting, and we apply SLND virtually in all clinical situations even in those which were previously considered a contraindication for this procedure. Basically, our policy is to perform SLNB always unless documented axillary métastases are present.