What are lymph nodes?

Lymph nodes are small lumps of tissue that contain white blood cells, which fight infection. They filter lymph fluid, which is composed of fluid and waste products from your body tissues. Lymph nodes also help activate your immune system if you have an infection.

Where are lymph nodes located?

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

How lymph nodes filter lymph fluid

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

The filtered fluid is then returned to your 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.

Lymph nodes and cancer

Sometimes cancer can start in the lymph nodes (such as in lymphoma), but 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.