Doctors classify lymphedema as primary (hereditary) or secondary. Several genetic conditions can cause lymphedema, and your risk is higher if you have a close relative with lymphedema. However, your doctor can look out for this condition and address it before it becomes too big a problem.
The highest number of secondary cases occur as a result of cancer treatment. Cancer surgery or radiation may disrupt the lymphatic draining since surgeons often remove lymph nodes during cancer surgery. The cause for the slowdown in drainage may remain unknown in some cases. Obesity and older age may contribute.
Lymphedema can also be a common symptom of advanced chronic venous insufficiency. In this case, blood that cannot return to the heart because of damaged veins begins to leak out of the vessel, causing the swelling of lymphedema.