The benefits and limitations of sentinel lymph node biopsy

The status of the axilla is the single most important prognostic indicator of overall survival in patients with breast cancer. Staging is based on tumor size and on the presence of lymph node metastases. The number of lymph nodes, although prognostic, no longer impacts treatment options. Sentinel lymph node (SLN) mapping and dissection is a more sensitive and accurate technique for nodal evaluation and has been applied to staging of axillary lymph nodes in patients with breast cancer, providing prognostic information, with less surgical morbidity than with axillary lymph node dissection (ALND). When analyzed by an experienced pathologist with serial sectioning and immunohistochemical evaluation, SLN is the most accurate detection tool used in staging of breast cancer. In many centers that use these staging principles, ALND is no longer performed for histologically negative axillary SLNs. In addition, this technique may also be therapeutic because in most patients, the SLN is the only positive axillary node. SLN biopsy is justified in women with ductal carcinoma in situ who have a high risk of invasive carcinoma, such as those with large tumors, a mass, or high-grade lesions. SLN biopsy is performed in the setting of neoadjuvant chemotherapy and demonstrates accurate evaluation of the axilla in 90% of the cases. Women with locally advanced breast cancer may derive great benefit from a minimally invasive approach to the axilla because the extent of nodal involvement is unlikely to change further treatment. For clinically palpable nodes, ALND should be performed for therapeutic and local control. The use of sentinel node mapping in pregnancy is controversial. Vital blue dye is contraindicated in pregnant patients, although some have used radioactive colloid alone to map this subgroup of patients.