The lymph nodes reveal information about outlook and they help doctors determine the best types of treatment against the cancer. Your lymph nodes act as filters for your body's lymphatic drainage system. That's why the lymph nodes are likely to "catch" or filter out cancer cells that might be floating in the fluid that drains away from the cancerous area of the breast.
The surgeon will inject a blue dye and a radioactive substance (called a tracer) into the tumor or the skin over the tumor. The first lymph nodes that turn blue and pick up the tracer are called the sentinel (meaning "first") lymph nodes. The lymph node or nodes are then removed and sent to the pathologist, who looks to see if they contain any cancer cells. If no cancer cells are found, then no additional lymph node surgery is done.
If cancer cells are found in the nodes, then more underarm lymph nodes usually need to be removed. This is called an axillary (the armpit area) lymph node dissection (removal). There are three levels of axillary lymph nodes:
- Level I is the lowest level, closest to the breast.
- Level II is under a main muscle that sweeps through the armpit (pectoralis major).
- Level III refers to the lymph nodes just above this muscle.
A standard axillary lymph node dissection removes the lymph nodes from levels I and II. If the lymph nodes feel or look abnormal before surgery, then the standard axillary lymph node removal is usually done. Your surgeon may still use the dye, tracer, or both to make sure that all of the important lymph nodes are identified and removed.
A potential side effect of lymph node removal is lymphedema of the arm. This is a buildup of lymph fluid in the soft tissues of the arm along with swelling (also called edema). You can think of lymphedema as a plumbing problem: Veins and lymphatic channels are like pipes and drains that can handle the normal load of lymphatic fluid. If lymph nodes and channels are removed, there might not be enough pipes and drains to handle all the fluid and the arm swells.
Lymphedema can happen just weeks after lymph node surgery or years after initial cancer treatment. Factors that can bring on lymphedema include:
- Traumas to the muscles or skin of the arm that can lead to infection. These include scratches, bug bites, sunburn, kitchen burns, garden cuts, plant rashes (poison ivy or oak), skin cracking from chronic dryness, and skin tears from nervous picking habits.
- Gaining a lot of weight after breast cancer treatment. Like being overweight to start with, gaining weight increases your risk for arm swelling.
- Heat. Heat widens blood vessels and increases circulation to the arm. As a result, the extra fluid can seep into the tissues of the arm. The drainage pipes (lymphatic channels) of the arm may not be able to handle the extra fluid load, leading to swelling. Very hot weather and sitting in hot tubs can bring on lymphedema.
- Blood clots. Occasionally, a blood clot in the axillary (underarm) vein will back up fluid in the arm.
- Long plane flights. Although it's rare for a long flight to bring on lymphedema for the first time, it may worsen an existing case of lymphedema because of the changes in air pressure.
- Extensive breast cancer in the lymph nodes. This uncommon cause of lymphedema can occur if the cancer fills the lymph nodes and blocks the free flow of lymph fluid trying to drain through those nodes.
If you are free of lymphedema, it means that your body has no block in the free flow of lymph fluid through the lymph nodes. Or perhaps your body has already learned how to re-route any excess buildup of lymphatic fluid. Unfortunately, once you've developed lymphedema, the more you have and the longer you have it, the harder it is to reduce the swelling in your arm. Learn more about preventing and managing lymphedema.
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