Lymphoma, non-Hodgkin - Causes of non-Hodgkin lymphoma

Non-Hodgkin lymphoma is caused by a change (mutation) in the DNA of white blood cells called lymphocytes, although the exact reason why this happens is not known.

The DNA gives the cells a basic set of instructions, such as when to grow and reproduce. The mutation in the DNA changes these instructions so that the cells keep growing. This causes them to multiply uncontrollably.

The abnormal lymphocytes usually begin to multiply in one or more lymph nodes in a particular area of the body, such as your neck or groin. Over time, it is possible for the abnormal lymphocytes to spread into other parts of your body, such as your bone marrow, spleen, liver, skin and lungs.

In some cases however, non-Hodgkin lymphoma first develops in an organ or elsewhere outside the lymphatic system (the network of lymph vessels and glands found throughout the body).

Who is most at risk?

While the cause of the initial mutation that triggers non-Hodgkin lymphoma is unknown, a number of factors can increase your risk of developing the condition:

having a medical condition that weakens your immune system, such as HIV
having medical treatment that weakens your immune system – for example, taking medication to suppress your immune system following an organ transplant
having an autoimmune condition (a condition caused by problems with the immune system), such as lupus or Sjogren's syndrome
being previously exposed to the Epstein-Barr virus (a common virus that causes glandular fever)
being previously exposed to the Human T-cell lymphotropic virus (HTLV)
having a Helicobacter pylori infection (a common bacterial infection that usually infects the lining of the stomach and small intestine)
having received chemotherapy or radiotherapy for an earlier cancer
having coeliac disease (an adverse reaction to gluten that causes inflammation of the small bowel)

Non-Hodgkin lymphoma isn't infectious and isn't thought to run in families, although your risk may be slightly increased if a first-degree relative (such as a parent or sibling) has had lymphoma.

Non-Hodgkin lymphoma can occur at any age, but most cases are diagnosed in people over 65. The condition is slightly more common in men than women.