The status of the axillary lymph nodes is one of the most important prognostic factors in women with early stage breast cancer. Histologic examination of lymph nodes is the most accurate method for assessing spread of disease to these nodes. (See "Management of the regional lymph nodes in breast cancer" and "Prognostic and predictive factors in metastatic breast cancer", section on 'Prognostic versus predictive factors'.)
Axillary lymph node dissection (ALND) has traditionally been a routine component of the management of early breast cancer. The benefits of ALND include its impact on disease control (ie, axillary recurrence and survival), its prognostic value, and its role in treatment selection. However, the anatomic disruption caused by ALND may result in lymphedema, nerve injury, and shoulder dysfunction, which compromise functionality and quality of life.
ALND is the typical approach for women who have clinically palpable axillary nodes or positive nodes confirmed by methods such as ultrasound guided fine needle aspiration. For patients who have clinically negative axillary lymph nodes, sentinel lymph node dissection (SLND) is a method of staging the axilla with less morbidity than ALND.
Indications for and outcomes of SLND will be reviewed here. The technique of SLND in patients with breast cancer is discussed separately. (See "Sentinel lymph node biopsy in breast cancer: Techniques".)
DEVELOPMENT AND VALIDATION OF THE SLND TECHNIQUE
The importance of the sentinel lymph node (SLN) is based upon the observation that tumor cells migrate from a primary tumor metastasize to one or a few lymph nodes (LNs) before involving other LNs. Injection of vital blue dye and/or radiolabeled colloid around the area of the tumor permits identification of a SLN in the majority of patients, and its status accurately predicts the status of the remaining regional LNs (picture 1 and image 1 and image 2 and image 3). (See "Sentinel lymph node biopsy in breast cancer: Techniques".)