Appropriate axillary staging is a critical component of breast cancer care. In addition to being an important prognostic factor, nodal status and the extent of nodal disease affects decisions regarding surgical management as well as recommendations about systemic therapy and adjuvant radiation.
As recently as the early 1990s, axillary status was determined by axillary lymph node dissection (ALND) for all breast cancer patients regardless of clinical nodal status. Although ALND is accurate in identifying lymph node metastases and staging the axilla, it is also associated with potential morbidity including lymphedema, shoulder dysfunction, pain, and paresthesias.1,2 In addition, ALND identifies nodal metastases in only 20% to 35% of women who present with clinically node-negative disease.3-5 Because removing healthy lymph nodes provides no benefit, a more selective approach for axillary staging was required. Sentinel lymph node (SLN) dissection (SLND), which allows for accurate nodal staging with less morbidity than ALND, represents such an approach.2,6,7
The SLND procedure has been validated in numerous single-institution and multicenter studies and prospective randomized trials.5,8-11 For patients with clinically node-negative disease, SLND is now standard for axillary evaluation, and ALND can be omitted in patients with a negative SLN without diminishing disease-free survival (DFS), overall survival (OS), or local-regional control. Although completion ALND in patients with a negative SLN was abandoned soon after the adoption of the SLND procedure, ALND continued to be recommended for patients with a positive SLN. However, this practice has been called into question, and recent studies have shown that highly select patients with a positive SLN can also be spared ALND.12,13 The goals of this chapter are to discuss the clinical staging of the regional lymph nodes in breast cancer patients, review the SLND procedure, and discuss clinical trial results guiding the treatment of patients with clinically node-negative disease. An algorithm for managing patients with clinically node-negative breast cancer is shown in Fig. 78-1.
Algorithm for management of patients with clinically node-negative breast cancer. SLND, sentinel lymph node dissection; SLN, sentinel lymph node; ALND, axillary lymph node dissection; ITC, isolated tumor cell; BCT, breast-conserving therapy (breast-conserving surgery plus whole-breast irradiation); AxRT, axillary radiotherapy.
CLINICAL STAGING OF THE REGIONAL LYMPH NODES
Determining whether the tumor has spread to the local-regional lymph nodes is an important step in the initial staging of breast cancer. It provides prognostic information and helps determine appropriate management strategies. The clinical nodal stage is based on physical examination and radiologic studies. When performing a physical examination of the regional lymph nodes, if adenopathy is identified, the size of the palpable nodes should be noted. If axillary adenopathy is identified, whether the lymph nodes are mobile or matted should also ...