Sentinel Lymph Node Biopsy (SLNB) was originally developed for patients with penile cancer. In an effort to address the limitations of axillary lymph dissection,researchersin the 1980s and 90s adapted this technique for breast cancer patients.
Dr. Miltenburg in the operating room.
There are several areas in the body where a group of lymph nodes, known as a lymph node basindrains a relatively specific part of the body. Lymphatic vessels connect lymph nodes in the basin to each other. Examples of lymph node basins are the right and left axillary lymph nodes basins, which drain the breast on the same side.
There is usually onespecific node in a lymph node basinthat is the first node thelymphatic vessels from the area, such as the breast, drain to. The first node in a basin was dubbed the sentinel lymph nodebecause it was thought to act like a soldier or guard whose job is to stand and keep watch.
Theoretically, if a cancer cell breaks off the main tumor and travels through a lymphatic vessel system, it will lodge in the sentinel lymph node.Now the sentinel lymph node could kill the cancer cell (yay lymph node) or the cancer cell could multiply (tricky cancer cell). In the case of the multiplying cancer cell, a malignant daughter cell couldbreak away, pass beyond the sentinel node and travel through the lymphatic vessels to other nodes in the basin.
If it were possible to identify the sentinel lymph node and prove it did not contain cancer (negative SLN), one could be pretty certain there wasn’t cancer in the other lymph nodes. Studies show that when done properly, the chance of finding cancer in the other lymph nodes when the SLN is negative is 5% or less. Furthermore, if the sentinel lymph node is negative, an axillary lymph node dissection is not necessary.
Patients with lymph nodes that look normal on physical exam and imaging (clinically node negative) are candidates for sentinel lymph node biopsy (SLNB).
The exception to this is patients with locally advanced cancers and those with inflammatory breast cancer. They are not candidates for SLNB. They should undergo axillary lymph node dissection.
Now a surgeon cannot tell which lymph node in the axilla is the SLN just by looking. In order to identify the SLN, it has to be mapped. There are two ways to map the SLN.
Methylene blue has a few drawbacks:
The choice of mapping technique depends on the surgeon’s preference and patient circumstances as outlined above. Many times both techniques are used. If the patient has had neoadjuvant chemotherapy, it’s recommended that SLN mapping be done using both radiocolloid and methylene blue and that a minimum of 3 SLNs be removed. Regardless of the mapping technique, the procedure usually takes about one hour. A drain is not placed.