Lymphomas start in the lymphatic system, the network of vessels that runs throughout the body carrying fluid containing white blood and other important immune system cells. Lymph nodes respond to infections by releasing white blood cells called lymphoid cells into the blood stream to fight it off.
When someone has lymphoma, lots of abnormal lymphoid, or lymphoma, cells are produced within a particular lymph node.
These are the same cells that become cancerous in people who have leukaemia, another form of blood cancer. The difference is that leukaemia develops in the bone marrow and affects normal blood cell production. Lymphoma, on the other hand, develops in the lymphatic system and does not affect normal blood cell production.
In patients with lymphoma the cancer cells cluster in the lymph nodes and form tumours. These cells can also spill into the blood stream and spread the cancer around the body, including to other lymph nodes.
Non-Hodgkin lymphoma is a cancer that can affect any lymph node or related tissue in the body whereas Hodgkin lymphoma tends to affect the lymph nodes in the head and neck.
There are two main types of NHL:
B-cell NHL usually affects the lymph nodes in the abdomen, head or neck. Burkitt lymphoma is a rare type of B-cell NHL.
T-cell NHL tends to occur in the chest and is more likely in teenagers. Occasionally NHL can develop outside a lymph gland. This is called extranodal lymphoma.
The causes of NHL are not fully understood, however children with deficiencies of the immune system or who have been taking immunosuppressing drugs for a long-time are known to be at increased risk of NHL.
Both Hodgkin and non-Hodgkin lymphoma have been linked with the Epstein-Barr virus (EBV), however EBV is extremely common and most people who get it do not develop lymphoma. Several geographical areas are associated with particular types of lymphoma – such as the ‘endemic’ Burkitt lymphoma in Africa.
NHL accounts for about 60% of lymphoma in children, with around 85 children affected each year in the UK.
NHL affects all ages but is very rare among infants; incidence increases until the age of around four years and remains fairly steady for the remaining years of childhood. The incidence among boys is more than twice that among girls.
NHL can be treated successfully in the majority of children, with an overall five-year survival rate of 88%.
The success of treatment depends on the type, stage and grade of the lymphoma. Better outcomes are associated with early diagnosis and disease localised to one area of the body.
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