PL3-1: Advances in Axillary Surgery: Sentinel Nodes and beyond.
Authors: Smith BL 
Published: June 2012

Abstract
Axillary node status is one of the strongest prognostic factors in breast cancer patients. The presence of tumor in axillary nodes, and number of positive nodes, predicts risk of metastatic disease and long term survival.
In the past, axillary dissection provided both accurate evaluation of nodal status and excellent local control. However, complications of axillary dissection, including lymphedema, pain, and impaired arm function, have led to keen interest in alternatives to axillary dissection for local control and assessment of prognosis.
Sentinel node biopsy provides a low-morbidity alternative to axillary dissection for patients with clinically negative nodes. It was recognized that breast lymphatics converge in the axilla, delivering fluid, travelling tumor cells and dye particles to a small number of “sentinel” nodes. Sentinel node biopsy techniques take advantage of this lymphatic anatomy using dye injection intraoperatively to permit identification and removal of only the most important axillary nodes - those most likely to contain metastases. A negative sentinel node provides accurate staging and reliably predicts a low axillary recurrence rate, eliminating the need for dissection. Sentinel node mapping also allows study of the relationship between the size of a nodal metastasis and impact on prognosis. Sentinel node mapping techniques, morbidity, and data on the reliability of sentinel node biopsy will be reviewed.
40–50% of patients with a positive sentinel node will have additional positive axillary nodes, indicating a need for additional axillary treatment for local control. Completion axillary dissection was initially used for local control and prognostic assessment in patients with a positive sentinel node. Recently, the ACOSOG Z0011 trial showed that patients with 1 or 2 positive sentinel nodes who receive standard whole breast irradiation without further axillary surgery have equivalent local control as patients having completion axillary dissection. Axillary recurrence rates in the Z0011 trial were &lt;1% at 6.3 years follow-up in both the radiation alone and dissection arms. Changing axillary management algorithms resulting from these data will be discussed. Sentinel node biopsy can now replace axillary dissection for patients with negative nodes undergoing either lumpectomy or mastectomy. Sentinel node biopsy can also replace dissection for lumpectomy patients with 1–2 positive sentinel nodes where data on the precise number of additional positive axillary nodes is not needed for treatment decisions. At present, axillary dissection is still recommended for patients with palpable axillary nodes, 3 or more positive sentinel nodes, gross extranodal tumor, and positive sentinel nodes after neoadjuvant therapy, or for positive nodes in patients undergoing mastectomy. Trials of radiation instead of dissection in such patients are likely.
Management of the axilla will evolve further as options for assessment of tumor and host factors increase. Gene expression profiling may prove more important than primary tumor size and node status for predicting prognosis and guiding therapy - an approach already used in estrogen receptor positive tumors. Future options for incorporating axillary node status with tumor and host factors in breast cancer management will be considered.
Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr PL3-1.