Sentinel Node Biopsy and Axillary Surgery
When breast cancer spreads around the body it begins by spreading to the lymph nodes near the breast. A breast cancer cell enters the lymphatic channels that drain the breast and travel to the nearby lymph nodes, most commonly in the axilla (arm pit).
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It is important that we establish whether the cancer has spread to the lymph nodes or not. If the cancer has spread to the lymph nodes then your treatment before or after surgery may be more extensive and may include chemotherapy.
Sentinel Node Biopsy
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A sentinel lymph node biopsy samples the first few lymph nodes draining from the breast. Up to 3 sentinel lymph nodes are removed from the axilla at the time of your breast cancer surgery.
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Only a small number of lymph nodes (approximately 3 lymph nodes) are removed during a sentinel lymph node biopsy and so the associated risk of lymphoedema (swelling of the arm) is very low (<5%).
A radioactive tracer and blue dye are injected into the breast prior to the surgery and are used to identify the sentinel nodes during a sentinel lymph node biopsy.
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Although a sentinel lymph node biopsy can be performed for the majority of patients with breast cancer, not everyone with breast cancer is suitable for a sentinel lymph node biopsy. The sentinel lymph node biopsy is used to sample the axillary lymph nodes to see if they have cancer in them or not. If at the time of your diagnosis it is already known that your lymph nodes have cancer in them, a sentinel lymph node biopsy will be of no benefit and you will require an axillary dissection. You may also be unable to have a sentinel lymph node biopsy if you have previously had axillary surgery.
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Sentinel node biopsy is a very low risk procedure. Common complications are bleeding, fluid collection (seroma) and pain. The risk of lymphoedema is incredibly low, which is one of the reasons why we prefer this method. It is approximately 5% or less for sentinel node biopsy, whilst an axillary clearance (most of the nodes taken) is 20-30%. The most serious complication is anaphylaxis (severe allergic reaction) to the blue dye. This risk is 1 in 1,000.
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Axillary Lymph Node Dissection
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An axillary lymph node dissection involves the removal of all the axillary lymph nodes draining from the breast. The number of lymph nodes in the axilla varies from person to person. The number of lymph nodes removed at axillary lymph node dissection usually ranges from 10-40 and averages approximately 20 lymph nodes.
The risk of lymphedema (swelling of the arm) is higher with axillary lymph node dissection (15-20%) compared to sentinel lymph node biopsy (<5%). A drain tube is placed into the wound after an axillary lymph node dissection to help prevent fluid building up under the skin. After an axillary lymph node dissection you will also be recommended to commence shoulder exercises with physiotherapy.
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An axillary lymph node dissection is recommended when it is known that cancer cells have spread from the breast to the axillary lymph nodes. The aim of an axillary lymph node dissection is to remove all the lymph nodes in the axilla. This allows all cancer that has spread to the axilla to be removed and reduces the chance of the cancer coming back in the axilla. Decisions about the treatment of your breast cancer, including the role of chemotherapy, will be made based on the number of lymph nodes removed, the number of lymph nodes containing cancer cells, and the size of the cancer cells in the lymph nodes.