Read about the risk factors for non Hodgkin lymphoma (NHL).
What a risk factor is
Anything that can increase your risk of getting a disease is called a risk factor.
Different cancers have different risk factors. Having one or more of these risk factors doesn't mean you will get that cancer.
Age and gender
Although non Hodgkin lymphoma can happen at any age, around 6 in 10 of all cases (60%) are diagnosed in people aged 65 and over. Overall, NHL is slightly more common in men than in women.
Weakened immune system
People whose immune system is not working as well as it should are more likely to develop a lymphoma. Immunity can be lowered for the following reasons:
- taking drugs to stop organ rejection after a transplant
- HIV or AIDS
- being born with a rare medical condition that affects immunity
- autoimmune diseases
If you have autoimmune disease, your own immune system attacks your body tissue as it would attack a germ. Autoimmune diseases include rheumatoid arthritis, haemolytic anaemia, coeliac disease, Sjogren's syndrome and systemic lupus erythematosus.
A number of viruses and bacteria have been linked with an increased risk of non Hodgkin lymphoma. However, many of these infections are uncommon in the UK. So the actual number of cases caused by infections here is small.
The infection is only part of a complex process for cancer to develop. Most people with these infections don't go on to develop non Hodgkin lymphoma. And non Hodgkin lymphoma itself is not infectious.
T cell lymphoma virus 1 (HTLV1)
Infection with a virus called human T cell lymphoma virus 1 (HTLV1) can increase the risk of developing non Hodgkin lymphoma. HTLV1 is most common in Japan and the Caribbean.
Epstein Barr virus
The Epstein Barr virus is linked to an increased incidence of Burkitt's lymphoma, a type of non Hodgkin lymphoma that is more common in Africa than Europe. This is the virus that causes glandular fever (mononucleosis). People who have had mononucleosis might have a higher risk of developing non Hodgkin lymphoma.
A more common bacterial infection called Helicobacter pylori can cause a rare type of lymphoma that starts in the stomach. This type of lymphoma is called MALT lymphoma . MALT stands for mucosa associated lymphoid tissue. This means the lymphoma starts in lymphatic tissue outside the main lymphatic system. In this case, in the lining of the stomach.
People with the hepatitis C virus have 2 or 3 times the normal risk of getting non Hodgkin lymphoma. The hepatitis B virus also appears to increase the risk.
This is a disease of the small bowel. It affects about 1 in every 250 people. People with coeliac disease have an immune reaction to gluten, a protein found in rye, wheat and barley. This reaction causes inflammation of the small bowel.
For some time, coeliac disease has been a known risk factor for a rare type of lymphoma of the small bowel called enteropathy type T cell lymphoma (ETTL).
The risk seems to be higher in people with poorly managed coeliac disease. The risk in people with a diagnosis of coeliac disease has actually reduced over recent decades. If you have coeliac disease, sticking to a gluten free diet might help reduce your risk.
One study has also suggested that people who have a brother or sister with coeliac disease might also have an increased risk of developing non Hodgkin lymphoma.
Family history of non Hodgkin lymphoma
Having a parent, brother or sister diagnosed with non Hodgkin lymphoma slightly increases your risk of getting it. But this is not a major risk factor. The general risk is still small, and most people who get non Hodgkin lymphoma don't have a relative who has had it.
Previous cancer and treatment
Some other types of cancer, particularly blood cancers such as Hodgkin lymphoma and leukaemia, have been linked to an increased risk of non Hodgkin lymphoma. You might also be at a higher risk if you've had a melanoma.
Doctors are unsure whether this increase in risk is because of the effect of treatment for the first cancer, or because of the same risk factors that caused the first cancer. But these are very small increases in risk compared to the risk of not having the treatment for the original cancer.
Other possible causes
Stories about potential causes are often in the media. It isn’t always clear which of the ideas reported are supported by good evidence.
You might have heard about a possible cause which we haven’t included here. This is either because there is no evidence to support it, or because it is not fully clear what the evidence shows.