The lymphatic system

The lymphatic system helps protect us from infection and disease. Sometimes cancer cells can travel through the lymphatic system, to other parts of the body.

What is the lymphatic system?

The lymphatic system is part of the body’s immune system. It protects us from infection and disease. The lymphatic system is made up of:

  • Lymph vessels

    Lymph vessels are a network of tiny tubes throughout the body. They carry lymph fluid.

  • Lymph fluid

    This is a colourless fluid that flows through the lymph vessels. It is filtered through the lymph nodes. It then moves back into the bloodstream.

  • Lymph nodes (glands)

    Lymph nodes act like a filter for the lymph fluid. They remove germs (bacteria and viruses) and other harmful cells.

    Lymph nodes can be tiny like a pinhead or bigger like a baked bean. They are spread throughout the body. Some areas have groups of lymph nodes. These groups are mainly in the neck, armpits, groin, chest and tummy (abdomen). 

    You might sometimes be aware of your lymph nodes, such as the ones in your neck when you have a sore throat. They can feel sore or swollen for a short time while your body fights an infection. But if you notice a painless, swollen lymph node, it is important to get it checked by your GP.

Organs in the lymphatic system

The lymphatic system has several organs:

  • The spleen

    This controls some of our blood cells. It filters out and removes old and damaged red and white blood cells. It also contains white blood cells. These help protect us from infection.

  • The thymus

    The thymus is a small gland in the chest. It helps produce white blood cells. It is more active when you are a teenager and shrinks over time.

  • Tonsils and adenoids

    These help protect the lungs and digestive system from infections. Tonsils sit at the back of the throat. Adenoids are at the back of the nose.


The lymphatic system

The body’s lymph nodes are shown. There are nodes in the neck, armpit and groin. Lymph vessels are also shown throughout the body.
Image: The diagram shows the network of lymph nodes and vessels in the body. The nodes are small bean-shaped dots. There are nodes shown throughout the body, including in the neck (cervical), armpit (axilla) and groin (inguinal). The lymph vessels are shown all the way down the limbs, reaching the fingers and toes.


The lymphatic system of the head and neck

Lymph nodes are shown in the head, neck, and shoulders. They are connected by a network of lymph vessels
Image: The diagram shows a side view of a person’s head and shoulders. Lymph nodes and vessels are shown. The lymph nodes are small, bean-shaped dots. They are connected by a network of lines, which are the lymph vessels. There are lymph nodes shown behind the ear, in front of the ear and throughout the neck, from below the chin down to the shoulder.

What does the lymphatic system do?

The lymphatic system has different jobs:

  • It helps fight infection – inside the lymph nodes are white blood cells called lymphocytes. Lymphocytes attack and destroy bacteria, viruses, damaged cells and cancer cells. When lymph nodes are fighting an infection, they can get bigger and feel sore.
  • It removes waste products – the lymphatic system carries destroyed bacteria and other waste products back into the bloodstream. The liver and kidneys remove these from the blood. The body then gets rid of this waste when you pass urine (pee) or stools (poo).

The lymphatic system and cancer

Cancer can affect the lymphatic system in different ways:

Cancer cells may travel through the lymphatic system

Sometimes cancer spreads from one place in the body (the primary site) to another place. It can travel through the blood or the lymphatic system. When the cancer moves to somewhere else, it is called a secondary cancer or metastasis.

Cancer cells may spread into and grow in the lymphatic system

Sometimes cancer from another part of the body can spread into and grow in the lymph nodes. This is called lymph node metastases or secondary cancer in the lymph nodes.

Cancer may start in the lymphatic system

Lymphoma is a cancer of the lymphatic system. It develops when white blood cells called lymphocytes become abnormal. The most common symptom of lymphoma is a painless swelling or lump in the neck, armpit or groin. If you notice this, it is important to get it checked by your GP.

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About our information

  • Reviewers

    This information has been written, revised and edited by Macmillan Cancer Support’s Cancer Information Development team. It has been reviewed by expert medical and health professionals and people living with cancer. It has been approved by members of Macmillan’s Centre of Clinical Expertise.

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We want everyone affected by cancer to feel our information is written for them.

We want our information to be as clear as possible. To do this, we try to:

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We use gender-inclusive language and talk to our readers as ‘you’ so that everyone feels included. Where clinically necessary we use the terms ‘men’ and ‘women’ or ‘male’ and ‘female’. For example, we do so when talking about parts of the body or mentioning statistics or research about who is affected.

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Date reviewed

Reviewed: 01 January 2024
Next review: 01 January 2027
Trusted Information Creator - Patient Information Forum
Trusted Information Creator - Patient Information Forum

Our cancer information meets the PIF TICK quality mark.

This means it is easy to use, up-to-date and based on the latest evidence. Learn more about how we produce our information.