The causes of lymphoma are mostly unknown. But some things may increase the risk of developing it,  such as having a weakened immune system. These are called risk factors. Having one or more of these risk factors does not mean you will get lymphoma. Many people with lymphoma do not have any risk factors.

Risk factors of Hodgkin lymphoma

Age

Hodgkin lymphoma is more common in people over 70. But it can happen at any age. It is one of the most common cancers in people in their teens and early 20s.

Gender

Lymphoma is slightly more common in men than women.

Infection

The Epstein Barr virus (EBV) is sometimes linked to Hodgkin lymphoma. EBV is the virus that causes glandular fever. It is very common in the UK and does not usually cause serious illness. It is rare to develop lymphoma because of an EBV infection. Lymphoma is not infectious and cannot be passed on to other people.

A weakened immune system

If your immune system is weak, you have a higher risk of developing lymphoma. Conditions such as HIV can weaken the immune system.  Drugs called immunosuppressants can also weaken the immune system. Some people need these drugs after an organ transplant or to treat auto-immune disease.

Having a close relative with lymphoma

People who have a parent, brother or sister with lymphoma, have higher risk of developing Hodgkin lymphoma. The reason for this is not known. It may be because there is a genetic change that runs in families. Or it could be because people within one family tend to have the same lifestyle factors.

This risk is very small. Most people who have a close relative with lymphoma will not develop lymphoma.

Risk factors of Non-Hodgkin lymphoma (NHL)

Age

NHL can affect people at any age. But it is more common in people who are over 50.

Gender

Lymphoma is slightly more common in men than women.

Infections

Some viruses or bacteria can increase the risk of developing NHL:

• Helicobacter pylori infection sometimes causes a type of NHL called MALT lymphoma.
• Epstein Barr virus (EBV) infection, which causes glandular fever, may slightly increase the risk of developing some types of NHL.
• Hepatitis C virus (HCV) can slightly increase the risk of splenic marginal zone lymphoma (SMZL).
• Human T-lymphocytotrophic virus-1 (HTLV-1) is a rare infection that is linked with T-cell lymphoma in some people.

Most people who have had these infections will not develop lymphoma. Lymphoma is not infectious and cannot be passed on to other people.

A weakened immune system

If your immune system is weak, you have a higher risk of developing lymphoma. Conditions such as HIV can weaken the immune system. We have more information about lymphoma and HIV.

Drugs called immunosuppressants can also weaken the immune system. Some people need these drugs after an organ transplant or to treat auto-immune disease.

Auto-immune disease

Auto-immune diseases develop when the immune system attacks healthy body tissue by mistake. Several auto-immune diseases can increase the risk of lymphoma. These include:

• coeliac disease
• Sjogren’s syndrome
• rheumatoid arthritis
• systemic lupus erythematosus.

Doctors do not fully understand why these diseases increase the risk of developing lymphoma. It may be because of the diseases themselves, or the treatments used to control them.

A previous cancer

NHL is slightly more common in people who have had cancer before. This may be because of the cancer or because of the cancer treatments. Radiotherapy and some chemotherapy drugs can increase the risk of developing NHL many years later. But the risk is small compared to the benefit of having the treatment.