The lymphatic system consists of various glands, organs and ducts connected throughout the body. It removes lymph (fluid containing white blood cells, plasma and other substances) from the tissues and returns it to the bloodstream. The lymphatic system is an important part of the immune defense system. In addition to extracting lymph fluid from tissues, the lymphatic system produces and stores some of the cells needed by the body to fight infections and diseases, including cancer.  

Lymph is transported throughout the body in tubes known as lymph vessels. Without lymph vessels, the lymph fluid would collect in the tissues and cause swelling. Located along the lymph vessels are lymph nodes (small, bean-shaped organs clustered in various areas of the body). Their functions include producing immune cells to fight infection and filter bacteria and other foreign material from lymph. 

In addition to the lymph fluid, lymph vessels and lymph nodes, the lymphatic system also involves a number of organs and tissues, including:

• Spleen. An organ involved in the detruction of worn-out or damaged red blood cells and platelets and in the production of certain white blood cells.
  
  
• Thymus. An organ responsible for developing T lymphocytes (T cells) during fetal development.
  
  
• Bone marrow. The soft inner part of bone in which all forms of blood cells are produced.
  
  
• Adenoids and tonsils. Masses of tissue that produce antibodies against antigens or threats to the body, such as germs, mismatched red blood cells and cancer cells.

The lymphatic system is closely linked to cancer. It is an important factor in the body’s response against cancer, and is also one of the most common pathways for the spread of cancer cells to other areas of the body (metastasis).

Cancer of the lymphatic system is known as lymphoma. In addition to this group of diseases, a variety of other cancers may also develop in areas of the lymphatic system. These diseases include:

• Thymus cancer
• Multiple myeloma (bone marrow)
• Leukemia (bone marrow)
• Tonsillar cancer
• Adenoidal cancer
  
  

Cancers that do not start in the lymph system, such as breast cancer, can spread or metastasize to the lymph system easily. After the cancer cells are in the lymph system, it is much harder to contain the cancer, significantly affecting the patient’s prognosis for recovery.