Lymphoma is a cancer of the lymphatic system. The lymphatic system is made up of a series of vessels and glands, known as lymph nodes. These are spread throughout your body, much like your blood vessels.
The lymphatic system is part of your immune system. Clear fluid called lymph flows through the lymphatic vessels and contains infection-fighting white blood cells known as lymphocytes.
In lymphoma, these lymphocytes start to multiply in an abnormal way and begin to collect in certain parts of the lymphatic system, such as the lymph nodes. The affected lymphocytes lose their infection-fighting properties, making you more vulnerable to infection.
The most common symptom of lymphoma is a painless swelling in a lymph node, usually in the neck, armpit or groin (see Lymphoma – symptoms for more information).
There are two main types of lymphoma:
About 80% of all lymphomas diagnosed are non-Hodgkin’s lymphoma. The causes of both types of lymphoma are still unknown.
Non-Hodgkin’s lymphoma
Non-Hodgkin's lymphoma is the most common type of lymphoma. More than 9,700 people in the UK are diagnosed with non-Hodgkin's lymphoma each year.
Non-Hodgkin’s lymphoma refers to any type of lymphoma that does not have the distinctive Reed-Sternberg cell that is present in Hodgkin’s lymphoma (see below).
There are many sub-types of non-Hodgkin’s lymphoma, but they can all be put into one of two broad categories:
- high-grade or aggressive non-Hodgkin’s lymphoma, where the cancer develops quickly and aggressively
- low-grade or indolent non-Hodgkin’s lymphoma, where the cancer develops slowly and you may not have any symptoms for many years
Who is affected
Non-Hodgkin's lymphoma is associated with ageing, as the chances of developing the condition increase as you get older. The average age at diagnosis is around 65.
For reasons that are not understood, the rates of new cases of non-Hodgkin's lymphoma have been slowly but steadily rising for the last 50 years. The rate of increase in the UK is around 4% a year.
If the occurrence of non-Hodgkin's lymphoma continues to rise at the current rate, it is estimated that it will be as common as breast or lung cancer by 2025.
Outlook
Survival rates for non-Hodgkin’s lymphoma vary greatly depending on the exact type, grade and stage of the lymphoma, and the person’s age.
Despite their names, high-grade non-Hodgkin's lymphoma is easier to treat than low-grade non-Hodgkin's lymphoma. Cure rates depend on individual circumstances and the subtype of the lymphoma, but an average of 60% of people with high-grade non-Hodgkin's lymphoma are cured.
The difficulty with low-grade non-Hodgkin's lymphoma is that it does not cause symptoms until it is well advanced, by which time it is often too late to cure. However, it is possible to control symptoms for many years.
Hodgkin’s lymphoma
Hodgkin’s lymphoma is one of the rarer types of lymphoma, but it is one of the most common cancers among younger people. It is named after the doctor who first described the condition in the 19th century.
Hodgkin’s lymphoma is characterised by the presence of a distinctive abnormal cell known as a Reed-Sternberg cell (a B-lymphocyte that has become cancerous; see box).
Nearly 1,500 people are diagnosed with Hodgkin's lymphoma in the UK each year.
Who is affected
Hodgkin's lymphoma mostly affects young adults aged between 15 and 35 and adults over the age of 50. More men than women are affected.
Outlook
Hodgkin’s lymphoma is a relatively aggressive cancer and can quickly spread through the body. Despite this, it is also one of the most easily treated types of cancer.
Almost all young people with Hodgkin's lymphoma will be fully cured. For older people over the age of 50, the cure rate is around 75-80%.
