Sentinel Lymph Node Biopsy in Breast Cancer

The axillary lymph node status is the most reliable prognostic indicator of recurrence and overall survival in patients with breast cancer. The current standard surgical procedure for the management of invasive breast cancer is the complete removal of the cancer with total axillary clearance. However, recently, selective sentinel lymph node mapping and biopsy is gaining acceptance as a useful and accurate staging procedure, as it is minimally invasive. The sentinel lymph node is the first node into which a primary cancer drains, and is thus the first node to be involved by metastases. Patients whose sentinel nodes are negative for breast cancer metastases, can be spared a more extensive axillary lymph node dissection, with reduction in the postoperative morbidity. Sentinel node mapping is usually performed by intradermal or peritumoral injection of a combination of blue dye and radiotracer. Sentinel node examination is sometimes done intraoperatively, by imprint cytology and frozen sections, for an immediate assessment, to plan the extent of surgery at a single sitting. Permanent sections of the sentinel node are studied by serial sectioning, and immunohistochemistry for cytokeratin is done to detect micrometastases which are frequently missed on hematoxylin and eosin (H&E)-stained sections. The various aspects of sentinel node examination, and its role to decide further management in patients with ductal carcinoma-in-situ, and in other clinical settings, are discussed in this review.