Lymphomas are cancers of the lymphatic system. When a person has lymphoma, some of their lymphocytes (a type of white blood cell) are 'out of control'. They divide in an abnormal way or they do not die off when they should. These abnormal lymphocytes can collect in the lymph nodes, which then enlarge as the lymphocytes form tumours.
Lymphoma can affect lymph nodes in any part of the body. It can also involve other parts of the lymphatic system, such as the spleen or the bone marrow. Like other cancers, lymphoma can affect the function of the tissue involved. For example, someone with lymphoma in the bone marrow might not be able to make new blood cells.
Although lymphoma is a disease of the lymphatic system, it can also happen in other areas of the body. For example, lymphoma can affect the stomach, the skin or the liver.
For more information about lymphatic cancer read our lymphomas booklet.
The lymphatic system is a complex network of tubes (lymphatic vessels), glands (lymph nodes) and other organs such as the spleen and the thymus gland. We have lymph nodes and vessels throughout our bodies. These are often found in groups, particularly under the arms, in the neck and in the groin.
The lymphatic system is part of the body's natural defence against infection – the immune system. The vessels and glands hold a clear fluid called lymph. Lymph contains white blood cells called lymphocytes, which the body uses to fight infection. Lymphocytes are mainly found in the lymph nodes but circulate around the body in both the blood and the lymphatic system.
The lymphatic system also has a number of other functions. It drains waste products and excess fluid from the tissues throughout the body and moves them to the bloodstream to be processed. It also absorbs fats from the gut and transports them to the bloodstream.
There are many different types of lymphoma. Lymphomas are put into different categories – or classified – after a pathologist looks at the cells under a microscope and performs various tests.
The appearance of the cells gives an indication of how they will behave. Other tests give the pathologist information about the molecules present on the lymphoma cell and the changes that have occurred in its genes. All this information helps to put the lymphoma into a particular category.
Once these tests are completed, the pathologist can tell your specialist whether you have Hodgkin lymphoma or a non-Hodgkin lymphoma and how the disease might affect you. This information is very important for planning your treatment.
The diagnosis of lymphoma can be difficult. There are other diseases that look similar under the microscope and general pathologists might see very few cases of lymphoma in a year. It is now recommended that specialist pathologists review the biopsy specimens in all cases of suspected lymphoma.
Lymphomas develop as the result of changes that take place in the cell genes. These changes in the genes interfere with cell division and cell death so they begin to grow out of control. In most cases what has caused these gene changes is not known so the cause of lymphoma is not known.
What is known is that some people are more at risk of lymphoma. This is usually because of another medical condition they have, in particular medical conditions that interfere with the immune system, or because their immune system is artificially suppressed. Doctors also know that certain lymphomas grow as a result of particular viral infections, but these account for only a very small proportion of cases.
Lots of research studies have investigated possible causes of lymphoma. These studies have looked at factors like chemicals present in the working environment or the increased risk of lymphoma in some families, but it will be a long time before scientists understand this subject properly.
There is no firm evidence to suggest that anything you have done – or not done – has caused you to develop lymphoma. You can't catch lymphoma from someone and you can't give it to anyone else.
You could experience a wide range of symptoms of lymphoma. You might experience very few symptoms. Some people have no symptoms at all.
The most common symptom of lymphoma is:
- a painless lump or swelling, often in the neck, armpit or groin.
Other common symptoms include:
- excessive sweating, especially at night
- unexplained loss of weight
- unusual tiredness
- persistent itching
- a cough or breathlessness
- abdominal pain or diarrhea.
Your symptoms can vary according to which parts of your body are involved. For example, an enlarged lymph node might cause pain in the area around it. Lymphoma in the stomach might cause stomach ache.
Hodgkin lymphoma is named after Dr Thomas Hodgkin, who was the first person to document lymphoma in scientific papers in 1832.
Around 70 years later, two scientists called Dorothy Reed and Carl Sternberg looked at samples of Hodgkin lymphoma under the microscope. They found that there was a particular cell present in all cases. This became known as the 'Reed–Sternberg cell'. A century later, lymphomas are still categorised as a Hodgkin lymphoma if the Reed–Sternberg cell is seen under the microscope.
More than 1,800 people are diagnosed with Hodgkin lymphoma each year in the UK. Hodgkin lymphoma can occur at any age, but most people who develop it are between the ages of 15 and 35 or are over 55. Hodgkin lymphoma affects slightly more men than women.
Hodgkin lymphoma is now very successfully treated and the majority of people with it will be completely cured.
It might seem like a strange way to name an illness, but non-Hodgkin lymphoma simply means any lymphoma that is not Hodgkin lymphoma.
Over 12,200 people are diagnosed with non-Hodgkin lymphoma each year in the UK. It is more common in the over-55s and it is one of the most common cancers in people aged 75 and over.
There are many different types of non-Hodgkin lymphoma. Some types grow very slowly and others grow more quickly.
High-grade or aggressive non-Hodgkin lymphoma
Non-Hodgkin lymphoma is called ‘high-grade’ or ‘aggressive’ when the cells appear to be dividing quite quickly. Some types of high-grade non-Hodgkin lymphoma will grow faster than others.
The most common high-grade non-Hodgkin lymphoma is:
- diffuse large B-cell lymphoma.
Other high-grade non-Hodgkin lymphomas include:
- peripheral T-cell lymphoma
- Burkitt's lymphoma
- lymphoblastic lymphoma.
High-grade non-Hodgkin lymphomas are more common in people aged over 50, but they can occur at any age. Although the term 'high-grade' sounds alarming, these lymphomas often respond very well to treatment and can be cured in many cases.
Low-grade or indolent non-Hodgkin lymphoma
Non-Hodgkin lymphoma is called ‘low-grade’ or ‘indolent’ when the cells appear to be dividing slowly. This means that low-grade non-Hodgkin lymphoma can take a long time to develop.
The most common low-grade non-Hodgkin lymphoma is:
- follicular lymphoma.
Other low-grade non-Hodgkin lymphomas include:
- small lymphocytic lymphoma / chronic lymphocytic leukaemia
- marginal zone lymphoma
- MALT lymphoma
- lymphoplasmacytic lymphomas (including Waldenström’s macroglobulinaemia).
Some people have early-stage low-grade non-Hodgkin lymphoma (stage I or II) when they are first diagnosed. This can be cured in some cases.
Most people have advanced low-grade non-Hodgkin lymphoma (stage III or IV) by the time they are diagnosed. This is more difficult to cure completely. These lymphomas behave in a chronic way, sometimes active and sometimes inactive. Doctors aim to control advanced low-grade non-Hodgkin lymphoma rather than to cure it.
People with low-grade non-Hodgkin lymphoma can often go for long periods when they feel well and don't need treatment. This is often referred to as ‘watch and wait’.
Lymphoma is currently the fifth most common cancer diagnosed by clinicians in the UK (after breast, lung, colon and prostate cancers). It is the most common blood cancer.
Lymphoma can occur at any age. It is the most common cancer affecting the under-30s and around 1 in 10 cancers diagnosed in children are lymphomas.
Each year in the UK, around 1,800 people are diagnosed with Hodgkin lymphoma and more than 12,200 people are diagnosed with non-Hodgkin lymphoma.
It is estimated that approximately 75,000 people in the UK are currently living with lymphoma.
The incidence of lymphoma is increasing year on year, especially among the over-75s, but it is not known why this is happening.
Please note: If you have problems accessing the links to further information, it may be because you do not have Adobe Reader installed on your computer.
Latest incidence figures available from Cancer Research UK: http://info.cancerresearchuk.org/cancerstats/ (accessed April 2012)
LYM0133/FAQWeb/2012v6 This version 18.06.2012 Due for revision 01.10.2013