Breast cancer patients undergoing a mastectomy or breast-conserving procedure are candidates for axillary sentinel lymph node dissection (SLND) if there is no palpable or clinical evidence of axillary lymph node involvement. The finding of breast cancer metastases in axillary lymph nodes changes the staging of the disease, predicts the rate of recurrence and survival, and results in adjuvant treatment with chemotherapy, hormone therapy, or radiation therapy. The standard axillary lymph node dissection (ALND) of level I and II nodes has significant morbidity, of which lifelong lymphedema is the most feared by patients. Using a combination of radionuclide and dye injections, the correlation of SLND and standard ALND in finding positive lymph nodes is quite high (95%) in the hands of an experienced surgeon. Although at least one sentinel lymph node can be identified in the majority of cases, in a small percentage, identification may not be possible, necessitating complete axillary node dissection. In addition, a false-negative finding occurs in 3% to 10% of the patients having SLND—that is to say, the sentinel nodes are negative, but higher nodes are found to be positive. The advantages of SLND are the fewer complications versus ALND and the ability to identify sentinel lymph nodes that are not in the traditional level I or II areas. The identification of sentinel lymph nodes focuses the histopathologic examination, which may include immunohistochemical staining as well as the traditional hematoxylin and eosin (H&E). The importance of micrometastases (<2 mm) is under study; however, the total number of nodes involved with metastases may influence the adjuvant therapy that is offered. Contraindications to SLND include suspicious, palpable axillary lymphadenopathy; and regional breast operations (e.g., breast reduction) that alter normal lymphatic flow. Sentinel lymph node biopsy may be considered after prior axillary surgery, but lymphatic mapping may be necessary to identify alterations in drainage patterns and the identification rate of sentinel nodes may be lower.
The skin should be free of infection, as should the preceding breast biopsy site. The preparation, delivery, and monitoring of the radionuclide solution for injection must be coordinated with the nuclear medicine staff.
General anesthesia with endotracheal intubation is preferred, as some patients will also have ALND and may be having a concurrent operation upon the breast. Most surgeons prefer that the anesthesiologist uses a short-acting muscle paralyzing agent for placement of the endotracheal tube such that the motor nerves can still be identified with mechanical stimulation during the ALND.
The patient is placed in a comfortable supine position with the arm out at 90 degrees on a padded arm board (figure 1). This position allows easy access of the breast and axilla. Some prefer to wrap the arm, including the hand, in sterile drapes so that the arm can be moved upward as well as medially to facilitate the subsequent dissection.
Approximately 90 minutes before the start of the operation, the surgeon injects the radionuclide solution into the breast, using sterile technique. A commercially available sulfur colloid solution using a technetium-99m tag is sterilized after passage through a 0.22-μm filter. Many techniques are used for injection of the radionuclide and blue dye. The injections may be placed (1) deeply about the tumor or biopsy ...