What are lymph nodes?

Lymph nodes (or lymph glands) are small lumps of tissue that contain white blood cells, which fight infection. They are part of the body’s immune system and filter lymph fluid, which is composed of fluid and waste products from body tissues. They help fight infections, and also play an important role in cancer diagnosis, treatment and the chance of recovery or recurrence.

Where are lymph nodes located?

Lymph nodes are located throughout the body, including the neck, armpits, groin, around the gut, and between the lungs. Lymph nodes drain lymph fluid from nearby organs or areas of the body.

How do lymph nodes filter lymph fluid?

Lymph fluid is carried to the lymph nodes by lymphatic vessels. The lymph nodes filter out harmful substances and waste products. They also contain immune cells called lymphocytes that destroy cancer cells and bacteria.

The filtered fluid is then returned to the blood circulation.

If you have an infection or cancer, a lymph node may become swollen. If you are concerned about your lymph nodes, speak to your doctor.

How are lymph nodes and cancer related?

Sometimes cancer can start in the lymph nodes (such as in lymphoma), but some others types of cancer can also spread from one part of the body to another through lymph nodes.

If a person has cancer, doctors examine lymph nodes carefully to see whether or not they are affected by cancer. They can do this by:

• feeling all the nodes in the body
• getting scans, for example a CT scan
• removing nodes near the cancer, then examining them under a microscope
• taking a biopsy of the lymph nodes near the cancer, then examining them under a microscope

This is done to see if the cancer has spread or not. This helps doctors work out the best treatment for the cancer.

Having swollen lymph nodes is only very rarely a sign of cancer. Lymph nodes may be swollen due to infection or inflammation. Swollen lymph nodes may be in the neck, under the arm or anywhere else there are lymph nodes. They can swell up to several centimetres and may stay swollen for weeks after the infection has cleared up.