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Lymphedema (limf-uh-DEE-muh) is a build-up of lymph fluid in the fatty tissues just under your skin.

What is the lymph system?

Our bodies have a network of lymph nodes and lymph vessels that collect and carry watery, clear lymph fluid, much like veins collect blood from distant parts of the body (like the hands and arms) and carry it back to the heart.

Lymph fluid contains proteins, salts, and water, as well as white blood cells, which help fight infections.

In the lymph vessels, one-way valves work with body muscles to help move the fluid through the body.

Lymph nodes are small collections of tissue that work as filters for harmful substances and help fight infection.

The lymph system in the upper body

What causes lymphedema?

During surgery for breast cancer, the doctor might take out lymph nodes from under the arm to see if the cancer has spread. When lymph nodes are removed, lymph vessels that carry fluid from the arm to the rest of the body are also removed because they go through and are wrapped around the nodes.

Removing lymph nodes and vessels changes the flow of lymph fluid in that part of the body. With breast cancer, it makes it harder for fluid in the chest, breast, and arm to flow out of these areas. If the remaining lymph vessels can’t drain enough fluid from these areas, the fluid builds up and causes swelling, or lymphedema.

Radiation treatment to the underarm lymph nodes can also affect lymph fluid flow in the arm, chest, and breast area by causing scarring and damage. This further increases the risk of lymphedema.

In most cases, lymphedema develops slowly over time. The swelling can range from mild to severe. It can start soon after surgery and/or radiation treatment. But it can also start months or even many years later.

Who gets lymphedema?

Any woman whose lymph nodes are affected by breast cancer treatment can get lymphedema. But women who have many lymph nodes removed and women who have had radiation therapy for breast cancer have a higher risk of lymphedema.

Doctors still don’t fully understand why some patients are more likely to have problems with fluid build-up than others.

It’s expected that in the future fewer women will have lymphedema because:

  • Breast surgery and treatment keep getting more conservative. (That is, more women are treated with breast-conserving surgery, which removes the cancer and a small amount of healthy tissue around it, rather than mastectomy, which removes the entire breast and more lymph nodes.)
  • Research advances have led to procedures like sentinel lymph node biopsy, which allows the surgeon to remove fewer lymph nodes.
  • Studies are looking at ways to find the lymph nodes that drain the arm before surgery so they can be saved when possible. This is called axillary reverse mapping.

Why do I need to know about lymphedema?

There’s still a lot to be learned about lymphedema, and there’s no way to predict who will develop it. But there are things you can do to care for your arm and breast area to reduce your chances of getting it.

Once lymphedema has started, it can’t be cured. Still, early and careful management can reduce symptoms and help keep it from getting worse. In fact, some women manage their lymphedema so well they become convinced they no longer have it.

Here you will find what we know about lymphedema, the signs you can look for, steps you can take to lower your risk of getting it, and things you can do to try to keep it from getting worse. Talk to someone on your cancer care team about your lymphedema risk and what you can do to lower your risk.

All women who have had episodes of lymphedema should follow the guidelines shared here and their cancer care team’s instructions to avoid the return or worsening of lymphedema.

Women who have had many lymph nodes removed and women who have had radiation therapy have a higher risk of lymphedema.


Last Medical Review: 07/10/2015
Last Revised: 07/10/2015