Women who have been treated for breast cancer may be at risk for arm, breast, and chest swelling called lymphedema (limf-uh-dee-muh). Most women who have had breast cancer will not develop this side effect, but many will. The risk of lymphedema is higher for women who have surgery and radiation therapy to treat breast cancer.

Here we will talk about what lymphedema is, the steps you can take to lower your risk, and what signs you can look for. There is no way to know who will get lymphedema. But there are things you can do to try to prevent it. And recognizing it early and starting treatment right away can help manage it.

What is the lymph system?

Our bodies have a network of lymph (limf) nodes and lymph vessels that collect and carry watery, clear lymph fluid, much like veins collect blood from all parts of the body and carry it through the body. Lymph fluid contains proteins, salts, and water, as well as white blood cells, which help fight infections. In the lymph vessels, 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 us fight infection.

What is lymphedema?

During surgery for breast cancer, the doctor removes at least one lymph node from the underarm area to see if the cancer has spread. Sometimes doctors remove more than one. When lymph nodes are removed, the lymph vessels that carry fluid from the arm to the rest of the body are also removed because they are wrapped around the nodes.

Removing lymph nodes and vessels changes the way the lymph fluid flows in that side of the upper body. This makes it harder for fluid in the chest, breast, and arm to flow out of this area. If the remaining lymph vessels cannot drain enough fluid from these areas, the excess fluid builds up and causes swelling, or lymphedema. Radiation treatment to the lymph nodes in the underarm can affect the flow of lymph fluid in the arm, chest, and breast area in the same way, further increasing the risk of lymphedema.

Lymphedema is a build-up of lymph fluid in the fatty tissues just under your skin. It usually develops slowly over time. The swelling can range from mild to severe. It can start soon after surgery or radiation treatment. But it can also begin months or even many years later. Women who have many lymph nodes removed and women who have had radiation therapy for breast cancer have a higher risk of getting lymphedema.

Doctors still do not fully understand why some patients are more likely to have problems with fluid build-up than others. They expect that in the future fewer women will develop lymphedema because:

• Breast surgery and treatment keep getting more conservative (that is, more women are treated with lumpectomy rather than mastectomy);
• Research advances have led to methods like the sentinel lymph node biopsy (a newer procedure that allows the surgeon to remove only 1 or 2 lymph nodes); and
• Newer studies are looking at finding which lymph nodes drain the arm before surgery so they can be preserved when possible. This procedure is called axillary reverse mapping.

There is still a lot to be learned about lymphedema, but there are ways that you can care for your arm and breast area to reduce your chances of having future problems. Once lymphedema has started, it cannot be cured. But early and careful management can reduce symptoms and help keep it from getting worse.