Sentinel lymph node biopsy as an alternative to routine axillary lymph node dissection in breast cancer patients

Sentinel lymph node (SLN) biopsy is a useful way of assessing axillary nodal status and obviating axillary lymph node dissection (ALND) in patients with node-negative breast cancer. Because SLN technology is evolving rapidly, however, variation in technique is widespread, and no standardization has yet been accomplished. This review discusses the feasibility and accuracy of this procedure and suggests the optimal method for identifying the SLN and detecting micrometastases. Although the SLN can be successfully identified by either the dye-guided or gamma probe-guided method in experienced hands, identification is facilitated when the two techniques are used together. In the gamma probe-guided method, the use of a large-sized radiotracer (particle size, 200-1000 nm) may be preferred because only one or two SLNs are identified. To increase the chance of finding metastases in SLN, it is desirable to make step sections with hematoxylin and eosin staining on permanent and frozen sections. The addition of immunohistochemistry may improve the accuracy of SLN diagnosis. The intraoperative examination of imprint cytology may be useful in determining the status of the SLNs, but further studies are needed to establish whether it has additional value when combined with the frozen section. In practice, routine ALND can be avoided when there is documentation of extensive experience and a low false-negative rate with the technique in the hands of a particular surgeon and hospital team. Particularly, SLN biopsy is more successful and has a lower false-negative rate in patients with smaller tumors. However, investigation of long-term regional control and survival in a prospective randomized trial is necessary, before SLN biopsy can replace routine ALND as the preferred staging operation for women with breast cancer.