The intraoperative assessment of sentinel nodes - Standards and controversies

Intraoperative assessment of sentinel lymph nodes (SLNs) has the advantage of allowing breast cancer patients with tumor-positive SLNs to avoid a second surgery by immediately proceeding to axillary lymph node dissection (ALND). However, there are several reasons why the use of intraoperative assessment should be questioned. Whereas ALND was traditionally advised for all breast cancer patients with tumor-positive lymph nodes for axillary staging and locoregional control, more recent studies have demonstrated safety of omitting ALND in a substantial number of patients. In addition, there are concerns about the accuracy of intraoperative assessment methods including frozen section analysis, touch preparation cytology and one-step nucleic acid amplification. Moreover, intraoperative assessment of SLNs denies patients the opportunity to contribute to their treatment planning. In our opinion, intraoperative assessment of axillary lymph nodes should be reserved for patients who still have a strict indication for ALND. Patients with clinical node negative disease (cN0) and one or two positive SLNs can be safely treated with breast conserving surgery and radiotherapy. There has been more controversy for cN0 patients who are treated with mastectomy since radiotherapy is not routinely administered in these patients. However, there is increasing evidence that ALND may be omitted in patients undergoing mastectomy who have a low tumor-burden in their SLNs. Therefore, we defend the position that in cN0 patients undergoing mastectomy, SLNB should be performed and full pathologic evaluation of the SLN should be awaited. In cN0 patients undergoing neoadjuvant systemic therapy (NST) intraoperative assessment of SLNs can be omitted since ALND will not provide therapeutic benefit. It is being hypothesized that patients with limited axillary disease prior to NST who remain node-positive after NST could be treated safely with axillary radiotherapy instead of ALND. In these patients, omitting intraoperative assessment might be a reasonable option. In patients with extensive nodal disease prior to NST intraoperative assessment of axillary lymph nodes should be performed.