Non-Hodgkin lymphoma

Non-Hodgkin lymphoma is a blood cancer that begins in the white blood cells called lymphocytes. It is sometimes called non-Hodgkin’s disease. It is one of the two main groups of lymphoma. The other group is Hodgkin lymphoma.

Most commonly, non-Hodgkin lymphoma starts in a lymph node at one or more places in the body. It can spread through the lymphatic system from one group of lymph nodes to another. It can also spread to other lymph tissue, particularly in the bone marrow and spleen, or to lymph nodes in the liver.

Sometimes non-Hodgkin lymphoma starts in or spreads to tissue in an organ outside the lymphatic system, such as the stomach, bone, skin, brain and spinal cord (central nervous system). This is known as extranodal disease.

Learn more about:

• What is blood cancer?
• The lymphatic system
• The role of blood cells
• Common types of non-Hodgkin lymphoma
• What causes non-Hodgkin lymphoma?
• Who gets non-Hodgkin lymphoma?

What is blood cancer?

Cancer is a disease of the cells. Cells are the body’s basic building blocks – they make up tissues and organs. The body constantly makes new cells to help us grow, replace worn-out tissue and heal injuries.

Normally, cells multiply and die in an orderly way, so that each new cell replaces one lost. Cancer develops when cells become abnormal and keep growing. When a cancer begins in abnormal blood cells, it is known as a blood cancer.

The three main groups of blood cancers are lymphoma, leukaemia and myeloma. Lymphoma is cancer of the body’s lymphatic system. In lymphoma, abnormal white blood cells called lymphocytes grow and multiply uncontrollably and can form a lump (tumour), usually in a lymph node. If these abnormal lymphocytes continue to build up, they can spread through the lymph vessels to form a tumour in another part of the lymphatic system. Occasionally, lymphoma travels through the bloodstream to form a tumour in an organ outside the lymphatic system, such as the liver or lung.

As the abnormal lymphocytes replace normal cells, the body’s immune system often becomes less able to fight infections.

Sometimes other types of cancer spread to the lymph nodes. This is not lymphoma. For example, breast cancer that has spread to the lymph nodes is still called breast cancer.

The lymphatic system

Non-Hodgkin lymphoma is a cancer of the lymphatic system. The lymphatic system is part of the immune system, which protects the body against disease and infection. The lymphatic system is made up of a network of vessels, tissues and organs:

Lymph vessels – These thin tubes are found throughout the body and in organs such as the spleen, liver, thymus gland and bone marrow. Lymph vessels carry lymph fluid around the body.

Lymph fluid – This clear fluid travels to and from the tissues in the body, carrying nutrients and taking away bacteria, viruses, abnormal cells and cell debris.

Lymph nodes (glands) – These small, bean-shaped structures are made up of lymph tissue. There are about 600 lymph nodes found in groups along the lymph vessels, including in the neck, underarms, chest, abdomen and groin. The lymph nodes filter lymph fluid as it passes through the body, before emptying most of the fluid into the bloodstream.

Anatomy of the lymphatic system

Other lymph tissue

As well as lymph nodes, lymph tissue is found in these parts of the body:

• bone marrow – produces blood cells
• thymus gland – helps produce white blood cells
• spleen – stores white blood cells, filters waste products from the blood, and destroys old blood cells, abnormal cells and bacteria
• tonsils – trap inhaled or ingested germs
• digestive system – stores immune cells.

The role of blood cells

The bone marrow is the soft, spongy material inside bones. It produces stem cells, which are unspecialised blood cells that usually grow into one of three main types of blood cells: red blood cells, white blood cells and platelets. Each type of blood cell has a specific function.

There are different types of white blood cells. The lymph nodes, lymph tissue and lymph fluid all contain the white blood cells known as lymphocytes.

Types of lymphocytes are B-cells, T-cells and NK-cells. B-cells make antibodies to fight infection. T-cells help the body fight invaders (antigens) by killing them directly or by helping B-cells make antibodies. NK-cells are rarer lymphocytes that specialise in killing cancer cells.

For more information about all types of blood cancers and the role of blood cells, visit the Leukaemia Foundation.

Common types of non-Hodgkin lymphoma

There are many different types of non-Hodgkin lymphoma, based on the type of lymphocyte affected (B-cell, T-cell or rarely NK-cell) and how fast the lymphoma is growing.

What causes non-Hodgkin lymphoma?

The causes of non-Hodgkin lymphoma are largely unknown, but the risk factors include:

Weakened immune system – The risk is higher if your immune system has been weakened. This can happen if you have an autoimmune disease, such as rheumatoid arthritis and coeliac disease, or if you need to take medicines that suppress the immune system after an organ transplant.

Certain viruses – Infections with Helicobacter pylori, HTLV-1 (human T-cell lymphotropic virus 1), hepatitis C, Epstein-Barr virus and human herpesvirus 8 can slightly increase the risk of non-Hodgkin lymphoma.

Family history – Having a parent, brother or sister who has had non-Hodgkin lymphoma slightly increases a person’s risk of developing it. However, this family link is rare.

Most people with known risk factors don’t develop non-Hodgkin lymphoma, and some people who do get it have no known risk factors. Non-Hodgkin lymphoma is not contagious.

Who gets non-Hodgkin lymphoma?

Each year in Australia, about 5000 people are diagnosed with non-Hodgkin lymphoma.  It is more common in men than women. Most cases occur in adults aged 60 and older. However, non-Hodgkin lymphoma can also occur in young adults and children.