SENTINEL LYMPH NODE BIOPSY
Axillary lymph node evaluation has been the standard of care in breast cancer treatment. This procedure involves the removal of two levels of lymph nodes from the axilla (armpit) to determine if the cancer has spread locally. This is considered part of the staging of the breast cancer and is routinely done at the time of the definitive breast cancer surgery.
One of the debilitating side effects of axillary dissection has been lymphedema (arm swelling). This occurs in approximately 8-12% of patients. The arm may also become numb above the elbow at the level of the triceps muscle. You must protect your arm from cuts and scrapes for the rest of your life to prevent lymphangitis (an infection in the lymphatics of the arm).
In an attempt to better diagnose lymph node metastasis and decrease complications associated with axillary dissection, a method of lymph node mapping adopted from melanoma treatment has been used to identify the sentinel (the first line of defense) lymph node. This lymph node can be evaluated for microscopic metastasis through various procedures from a frozen section done in the operating room to high tech evaluation called cytokeratin staining. It generally takes 7 days to receive the results and is far more sensitive than the naked eye of the pathologist. (It is unclear what the implication of cytokeratin positive cells in the sentinel lymph node means, therefore many centers have abandoned this as parat of their standard practice)
We know that women previously thought to be node negative; and therefore, have local disease, have died of distant metastasis. This may be related to our previous inability to find these microscopic metastatic deposits and treat them aggressively with chemotherapy.
The absolute answers to these questions still have not been completely resolved.
Sentinel lymph node identification is indicated in nearly all breast cancers and is appropriate in both lumpectomy and mastectomy patients. Parameters may vary from surgeon to surgeon and will be based upon your individual tumor characteristics. The procedure to identify the node starts with an injection of radioactive tracer called technetium sulphur colloid. It may be injected the day before surgery, the morning of surgery or as we do it in our practice in the operating room when you are asleep. It must remain in the breast for at least 8-12 minutes but can remain for 24 hours.
At the time of surgery, after you are asleep, a vital blue dye may be injected around the tumor bed. These two tracers act as guides that allow us to identify the sentinel lymph node (first line of spread) in > 90% of patients. When a sentinel lymph node is found at surgery, a frozen section (quick diagnoses) is performed. Once the sentinel node is identified, your surgeon will feel for other lymph nodes in your armpit that may have tumor in them. Lymph nodes filled completely with cancer cells may not have the ability to pick up the radioactive tracer and blue dye; therefore this is also an important part of the process.
If the frozen section reveals spread of cancer cells to the lymph node, additional lymph nodes (level I and II axillary node dissection) are removed. If the frozen section is negative for spread of the cancer, then no further lymph node surgery is performed at that time. At your postoperative visit, you will discuss your final pathology, which will include the results of your margins of tumor resection and the H & E staining and cytokeratin staining (high tech evaluation for spread) for tiny areas of tumor spread.
If the cytokeratin stains are positive and a micro-metastasis >.2mm is found, you may need to go back to the operating room for more lymph nodes to be removed(the completion of level I and II axillary node dissection )to complete your staging. The need for further surgery will be discussed with your surgeon and medical oncologist.
Frequently Asked Questions
1. If you identify a sentinel lymph node does that mean that the cancer has spread?
NO. Finding a sentinel lymph node only means that we are able to find a node or nodes that has taken up the tracer or blue dye. It only identifies the lymph node that is at the highest risk to have metastatic cancer in it.
2. Is the sentinel lymph node identification full proof?
NO. We believe that it is approximately 98% accurate in finding the first line of cancer spread. That means we could potentially miss 1-2% of cancer metastasis.
3. Can there be more than one sentinel lymph node?
YES. You can have several nodes show up with radioactive tracer. Usually only one is blue. On average 2 or 3 nodes are removed.
4. Can I have an axillary node dissection if I want one?
YES. Even if there is no evidence of spread in the sentinel lymph node, you are entitled to have levels I and II removed. It is still considered the standard of care.
5. What happens if you can’t find a sentinel node or if more than one lights up?
It is the surgeon’s judgment that determines if a node dissection needs to be completed. When in doubt, it is still the safest course and the surgeon should remove level I and II lymph nodes.
6. Why wouldn’t a sentinel lymph node show up?
Some tumors take a different route out of the breast and do not drain via the axillary lymphatics and therefore cannot be identified. Not finding a sentinel lymph node may also help the oncologist to determine the need for chemotherapy. Lymph nodes that are replaced completely with tumor may not take up the tracer.
7. What happens to the radio-labeled tracer and the blue dye?
It is excreted in the urine and therefore you will see blue urine for 24-48 hours after surgery. Your skin may also have a blue discoloration on the breast and systemically.
8. Do I have to spend the night in the hospital?
If you require an axillary node dissection you will have a drain and will be kept overnight. If your node /nodes are negative you should be able to go home the same day.
Allergic reactions to the Isosulfan BLUE
The incidence of allergic reactions in our series was 2.0%.
Severe life threatening reactions to the blue dye have been reported.
Anaphylaxis and "blue hives" after injection with isosulfan blue.Patients with anaphylaxis experienced cardiovascular collapse, erythema, perioral edema, urticaria, and uvular edema.
AXILLARY NODE DISSECTION
Axillary node dissection refers to the staging procedure performed in conjunction with lumpectomy for breast conservation or mastectomy. The procedure involves an axillary incision below the hairline when performed with a lumpectomy and is performed through the mastectomy incision with removal of the breast.
Removal of level I and II lymph nodes includes the tissue between the axillary portion of the breast and the area above the axillary vein underlying the pectoral muscles. The axillary nodes (level III nodes) lying above the pectoral major muscle are preserved to decrease the incidence of arm swelling (lymphedema). It may also remove a small nerve in the process resulting in numbness to the posterior aspect of the arm. Determining whether the lymph nodes are involved with the tumor will stage the cancer to determine if chemotherapy will be needed.
