What are lymphomas?

Lymphomas are cancers that begin with malignant changes in a type of white blood cell called lymphocytes. Over time these abnormal cells start to replace the normal lymphocytes and affect the working of the lymphatic system, an important part of the body’s immune system. The many types of lymphoma are classified into two main groups, ‘Hodgkin lymphoma’ and ‘non-Hodgkin lymphoma’. These diseases are also called Hodgkin’s disease or Hodgkin’s lymphoma; and non-Hodgkin’s disease or non-Hodgkin’s lymphoma.

All age groups affected

Lymphomas can develop at any age but the majority of lymphomas occur in people over the age of 50 years. However, the peak age for diagnosis of Hodgkin lymphoma is between 15 and 30 years.

Hodgkin lymphoma

Hodgkin lymphoma is cancer of the lymphatic system, and mainly affects the lymphocytes. Hodgkin lymphoma differs from non-Hodgkin lymphoma as it is characterised by the presence of a particular cell known as the Reed-Sternberg cell.

The cause, diagnosis and treatment of this disease is similar to that of non-Hodgkin lymphoma (below).

About non-Hodgkin lymphoma

Non-Hodgkin lymphoma is cancer of the lymphocyte, a particular type of white blood cell that is produced in the bone marrow, which travels in the blood to other parts of the body, normally the lymph glands. The lymph cells in these areas become malignant.

Cells are programmed similarly to computer software. Lymph cells become malignant by losing the part of their cell programme that teaches them how to grow and mature to carry out their function.

Lymphoma happens when the 'programme' inside a lymph cell becomes faulty and the growth and multiplication of the cells is no longer controlled or they fail to reach full maturity.

Enlarged lymph glands

Lymph gland tumours normally occur as enlarged lymph glands that can be felt or occasionally seen on x-rays of the chest or stomach. Most lymph gland enlargements are due to infection rather than malignant lymphoma and will resolve themselves.

Occasionally, lymph gland enlargements may occur as the result of the spread of cancer from other sites in the body, such as breast cancer, bowel cancer or lung cancer.

While enlarged lymph glands are the most common symptom, there is lymph tissue in all body organs and lymphoma may occasionally occur in other parts of the body such as the liver, lung or brain. Some lymph gland tumours spread back to the bone marrow to involve this organ in the disease.

What causes lymphoma? 

There is no known single or specific cause of lymphoma. The risk increases slightly in some patients with chronic infections, autoimmune diseases such as coeliac disease, or rheumatoid diseases such as rheumatoid arthritis.

People who have received long courses of chemotherapy for other diseases may also have increased risk of lymphoma.

Immuno-deficiency or deficiency of the immune system which has been inherited, or caused by viruses such as the AIDS virus, are also risk factors in developing lymphoma.

However, apart from highly specialised circumstances, there is no specific infectious cause and there are no known substances that cause lymphoma.

How is lymphoma diagnosed? 

If lymphoma is suspected, a blood test will be carried out to check for any abnormalities. This test might indicate an underlying malignant (cancerous) blood disease.

The test also gives a blood cell count and is useful for providing information on the likely behaviour of the lymphoma, as well as how the kidneys and liver are functioning.

Diagnosis is confirmed following a biopsy, a procedure in which a lymph gland is removed so the organisation and structure of the cells can be studied.

A combination of the individual cell appearance, the structure of the lymph gland and additional information from a number of other studies will show whether a lymphoma is present and whether it is low, intermediate or high grade.

Staging the disease

The lymphoma may occupy only one area in the body (stage 1) or it may have spread throughout the body (up to stage 4).The person's age, general medical condition and whether the lymphoma is low, intermediate or high grade will all have an effect on the prognosis (person's long term outlook).

Staging is the final step in determining the appropriate treatment plan but often a second series of tests are carried out before this happens.

Further tests may be needed

Further testing can take a number of forms and includes:

• Additional blood tests
• A lumbar puncture, where fluid is taken from the spine to undergo testing - to see if the lymphoma involves the brain or spine.
  
• A CT scan (computerised axial tomography) - a painless radiology procedure where pictures of the chest, abdomen and other parts of the body are fed into a computer to show a detailed view of the body. A special liquid may be given before the test to help outline the abdomen and occasionally injections are given into a vein to outline different organs. People usually lie on their back for about 10 minutes during the scan.

What is the treatment for lymphoma? 

Some types of lymphoma grow very slowly and do not need treating for a long time, if at all. Treatment for each person is determined by factors such as age, general health, type of lymphoma and whether it has spread to other parts of the body.

Other factors considered include the behaviour of an enzyme in the blood called lactate dehydrogenase (LDH) and another substance in the blood called beta 2 microglobulin.

The aim of treatment is to destroy as many malignant (cancerous) cells as possible and bring the disease into remission. There are a number of treatments that can be used to do this, but the main ones are chemotherapy, radiation treatment, or a stem cell or bone marrow transplant.

Related topics

See Lymphatic system and Blood cell types

Also see the everybody Human Atlas videos on Hodgkin lymphoma and non Hodgkin lymphoma

Original material provided by the Leukaemia and Blood Foundation of New Zealand, 2007. Edited by everybody, August 2010.