Sentinel node biopsy in breast cancer11No competing interests declared.

Determination of axillary nodal involvement is an integral part of management for patients with early stage breast cancer because axillary nodal status is the most important prognostic factor in this patient cohort. The presence or absence of metastases in the axilla often directs adjuvant systemic therapy in early stage breast cancer. A recent National Institutes of Health consensus conference recognized complete axillary lymph node dissection (ALND) as the gold standard for axillary staging. This is because of the axillary staging accuracy associated with ALND: a less than 2% false-negative rate. But the ability to achieve this level of accuracy is at the expense of considerable morbidity with this procedure; there is an acute complication rate of 20% to 30% and a chronic lymphedema rate as high as 20% to 30%. Because only about one third of patients with a clinically negative axilla have nodal metastases on histopathologic examination of the ALND specimen, routine ALND places a substantial number of patients at risk for operative morbidity without any known benefit from the operative procedure. There is a need for a less morbid and equally accurate method of assessing axillary nodal status. Until recently, assessment of axillary status using less invasive techniques has not achieved adequate clinical applicability. Physical examination of axillary nodal involvement is associated with false-negative rates of 29% to 38%. Assessment of axillary involvement with various radiographic methods (eg, mammography, computed tomography, and positron emission tomography) is also associated with an equally unacceptable false-negative rate. Limiting the extent of axillary dissection, thereby decreasing the complication rate, is not a comparable surgical alternative to ALND; there is a 40% falsenegative rate with random axillary nodal sampling and a 10% to 15% false-negative rate with excision of level I nodes alone. The recent introduction of sentinel node biopsy (SNB) in breast cancer patients provides a less invasive but equally accurate alternative of axillary assessment to ALND.