Last updated: 02/17/2009

The lymphatic system is responsible for returning excess fluid from body tissues to the circulatory system and for defending against foreign or harmful agents such as bacteria, viruses, or cancerous cells. The major components of the lymphatic system...

are lymph capillaries, lymph vessels, and lymph nodes. Lymph is a clear fluid found in tissues that originates from the circulatory system. Lymph capillaries are tiny vessels that carry excess lymph to larger lymph vessels; these in turn empty to the circulatory system. Lymph nodes are small, oval- or bean-shaped masses found throughout the lymphatic system that act as filters against foreign materials. They tend to group in clusters in such areas as the neck (cervical lymph nodes), under the arm (axillary lymph nodes), the pelvis (iliac lymph nodes), and the groin (inguinal lymph nodes).

The lymphatic system plays an important role in the spread of cancerous cells throughout the body. Cancer cells can break away from their primary site of growth and travel through the bloodstream or lymphatic system to other sites in body. They may then begin growing at these distant sites or in the lymph nodes themselves; this process is called metastasis. Removal of the lymph nodes, then, is a way that doctors can determine if a cancer has begun to metastasize. Lymphadenectomy may also be pursued as a cancer treatment to help prevent further spread of abnormal cells.