Breast cancer treatment with axillary lymph node surgery and radiotherapy, as well as high BMI and physical inactivity, increases the risk of arm lymphedema. Implementing screening for at-risk patients is beneficial for ensuring early diagnosis. Clinical assessments of skinfold thickness, local water content, and lymphedema volume are the most appropriate tools for detecting early lymphedema. When arm lymphedema is diagnosed early and is mild, it can be effectively managed over the long term.