The benefits of exercise outweigh the risks for breast cancer survivors and patients with lymphedema, a chronic swelling, U.S. researchers say. Jane Armer, a professor in the Sinclair School of Nursing at the University of Missouri, said patients at risk for lymphedema can exercise if they closely monitor their activities. \"Exercise can be beneficial and not harmful for breast cancer survivors,\" Armer said in a statement. \"Each individual should balance the pros and cons of the activity she chooses, but keep in mind that being sedentary has risks and being active is beneficial in many ways, including possibly reducing the risk of cancer recurrence.\" Lymphedema can occur any time after cancer treatment and is usually caused by the removal or radiation of lymph nodes as part of the treatment process, Armer said. Armer found patients who exercise had no greater risk for developing lymphedema than those who do not exercise, and patients with lymphedema did not worsen their condition by exercising. Future research is needed to determine whether exercise prevents the condition, Armer said. \"Breast cancer survivors do not need to restrict their activity as we once thought,\" Armer said. \"If patients want to be active, they should carefully condition their bodies by increasing repetitions of resistance exercises under proper supervision.\" The findings were published in the Journal of Cancer Survivorship and the Annals of Surgical Oncology.