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, lymph vessels that carry fluid from the arm to the rest of the body are also removed because they route through and are wrapped around the nodes.

Removing lymph nodes and vessels changes the flow of lymph fluid 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.

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 procedure that allows the surgeon to remove only 1 or 2 lymph nodes).
• 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.

Symptoms to look for include:

• achiness, tingling, discomfort, or increased warmth in the hand, arm, chest, breast, or underarm areas
• feelings of fullness or heaviness in the hand, arm, chest, breast, or underarm
• tightness or decreased flexibility in nearby joints, such as the shoulder, hand, or wrist
• “bursting” or “shooting” pain sensations, or pins and needles
• tenderness in the elbow
• slight puffiness or swelling in your arm, hand, chest, or breast, with a temporary indentation of the skin when you press on it with your finger (this is called pitting edema)
• veins or tendons in the hand are harder to see, and/or the knuckles look less pronounced, or once-wrinkled skin looks younger or smoother
• trouble fitting the arm into a jacket or shirt sleeve that fit well before
• bra feels tighter, does not fit the same, or leaves an indentation on the skin
• noticing that the two sides of the back look different in size (asymmetrical)
• difficulty getting watches, rings, or bracelets on and off
• changes in skin texture or appearance, such as tightness, redness, or hardening
• rash, itching, redness, pain, or warmth of the skin
• fever or flu-like symptoms

It’s never a good idea to wait out the symptoms to see if they get worse. The more time passes, the more likely it is that lymph will build up in the tissue. Once this happens, lymphedema can cause lasting damage, including changes in the appearance of the limb and the skin. Treating it is likely to take more of your time and energy than it would if you get help at the first sign of trouble.

Sudden swelling: Lymphedema usually happens gradually. However, some women have reported that their swelling came on suddenly. If you ever experience sudden severe swelling -- meaning that your hand, arm, or other body part seems to "blow up" to a larger size within a day or two -- see your doctor right away. It could mean that you have an infection, a blood clot (also known as deep vein thrombosis), or a recurrence of the cancer that is affecting the lymphatic system.