Take steps to prevent lymphedema. Lymphedema is a side effect of breast cancer treatment that involves swelling of the soft tissues of the arm, hand or chest wall. It isn’t life threatening, but it needs to be treated to avoid getting worse. The swelling may be accompanied by numbness, discomfort and infection. There’s no reliable way to assess your risk for lymphedema, but by taking proper precautions you can greatly reduce your chances of developing the condition. Ask your doctor about scheduling physical therapy if you notice symptoms, or consider seeing a physical therapist even before symptoms begin in order to minimize their chance of developing in the first place.