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How Lymphedema Happens

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To understand how and why lymphedema happens, you’ll want to get familiar with the lymphatic system.

Surgery and radiation therapy for breast cancer can remove or damage the important pathways of the lymphatic system: lymph vessels and nodes. Any of the body’s tissues that once depended on sending lymph through those pathways are at risk for fluid overload that leads to lymphedema. This can mean tissues in any part of the body on the treated side — such as the hand, arm, underarm, chest, and upper back (above the rib cage). Gradually, lymph builds up and the lymphatic system gets overwhelmed, resulting in swelling, discomfort, and other symptoms.

At first, the affected area can become slightly swollen, uncomfortable, and/or “tingly,” and then may get more noticeably swollen over time. (However, some women have reported that their swelling appeared to come on suddenly, without any warning signs.) If the lymphedema progresses, the limb (or other area) can become even more swollen, uncomfortable, heavy-feeling, and/or numb. Systemic infections can develop as a complication of lymphedema.

Individual studies have reported that as little as 10% up to as many as 90% of women develop lymphedema after breast cancer surgery and radiation therapy. Such a wide range of results may be due to the fact that: (a) researchers have used different ways of defining and then measuring lymphedema, (b) many of these studies have involved small numbers of patients, and/or (c) many studies were done with women who had a large number of underarm lymph nodes removed, which used to be standard practice. Today, many experts estimate that the range is probably close to 20-30%. Experts also have found a strong association between the extent of disruption to the lymphatic system and lymphedema risk. The more lymph nodes you have removed, and the more radiation you have to the underarm and chest, the higher your risk. Obesity and/or weight gain after treatment also increase risk.

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Expert Quote

"There are four very important things women should know about lymphedema: It tends to have a gradual onset. It tends to develop slowly. It tends to progress over time. And at first, it tends to cause symptoms that appear for a time and then get better — which in itself can be misleading, making it seem like everything is OK when it’s really not."

-- Nicole Stout MPT, CLT-LANA

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