Why remove four by chance when one will suffice?

Abstract

Breast cancer remains the most common cause of cancer in women and is the second leading cause of cancer death. The surgical management of breast cancer has evolved over the last 40 years from radical ablative procedures to breast conservation as the preferred method of treatment for early stage disease. The presence of axillary lymph node metastases remains the best prognostic indicator for patients with breast cancer and the mainstay of surgical management of breast cancer has included the removal of Level I, II and at times III axillary lymph nodes. The presence of axillary nodal metastases is often used to identify patients who would benefit from adjuvant treatment or a more aggressive adjuvant therapy regimen. However, over the last 10 years, the need for adjuvant therapy has often been based on the primary tumour characteristics and an increasing number of node-negative women are offered adjuvant therapy. This has led some to question the need for axillary surgery. Several methods have been used to identify breast cancer patients at risk of nodal metastases; however, none has been able to replace the need for histological evaluation of axillary lymph nodes. Fisher and colleagues [1] demonstrated that approximately 35% of nodes considered normal on physical examination contained carcinoma and 25% of enlarged suspicious lymph nodes on examination did not contain metastastic cells; therefore, clinical exam alone is not an accurate assessment of nodal status. Other radiological modalities such as computerised tomography, magnetic resonance imaging and mammography present similar difficulties with respect to determining the tumour status of lymph nodes. Positron emission tomography can identify nodal metastases larger than 1 cm, but its use would have limited value in the majority of patients [2]. In 1955, Berg popularised the anatomical subdivision of the axillary lymph nodes into three functional levels related to the pectoralis minor muscle [3]. Lymph nodes lateral and inferior to the pectoralis minor muscle are classified as Level I nodes, those located behind the pectoralis minor muscle are Level II nodes and nodes superior and medial to the pectoralis minor muscle are Level III nodes. Several types of axillary dissections are therefore defined by the Berg levels removed. A low axillary dissection removes Berg level I nodes, while a partial axillary node dissection removes Berg I and II levels and a total axillary node dissection removes all three Berg levels. Lesser procedures termed axillary sampling refer to the random biopsy of low axillary lymph nodes without anatomical reference [4]. The United States National Institutes of Health Consensus Conference in 1991 recommended that a Level I and II axillary lymph node dissection (ALND) be performed in patients with early breast cancer [5]. This is because axillary staging associated with this procedure is very accurate and has less than a 2% false-negative rate [6,7]. However, the ability to achieve this level of accuracy is at the expense of considerable morbidity: the most devastating to patients is chronic lymphoedema, which has been reported to occur in as many as 20–30% of patients in some series [8–10]. Because only approximately one-third of patients who present with breast cancer have nodal metastases, routine axillary nodal dissection places a substantial number of patients at risk for operative morbidity without any known benefit from the operative procedure. Attempts to reduce the morbidity of axillary node dissection with lesser procedures such as low ALND or axillary sampling have been abandoned due to high false-negative rates. There is a 40% false-negative rate with random axillary nodal sampling and a 10–15% false-negative rate with excision of Level I nodes alone [10–15]. The recent introduction of the sentinel node biopsy (SNB) provides a less invasive, but highly accurate, alternative of axillary assessment to axillary node dissection.