Causes and risk factors of NHL

In many cases, experts don’t know exactly what causes lymphoma. However, some things may in-crease the risk of developing it. 

It is important to remember that having these risk factors does not mean you will get lymphoma. Many people affected by lymphoma do not have any risk factors.


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

An infection called helicobacter pylori can sometimes cause a type of NHL called MALT lymphoma. The Epstein Barr virus (EBV), which causes glandular fever, may slightly increase the risk of developing NHL.

Both infections are very common in the UK. But most people who have had these infec-tions will not develop lymphoma.

Lymphoma is not infectious and cannot be passed on to other people.

A weakened immune system

If the body’s immune system is weak, the risk of developing lymphoma may be higher.

Conditions such as HIV can weaken the immune system. Drugs called immunosuppressants also cause this. Some people need this type of drug 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 conditions called:

  • rheumatoid arthritis
  • Sjogren’s syndrome
  • 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 because of the treatments used to control them.

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. Treatment with radiotherapy, or with 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 in the first place.

Having a close relative with NHL

Having a parent, brother or sister with NHL may mean you have a higher risk of developing it. But the risk of developing NHL is still low, with a lifetime risk of about 3 in 100 (3%). The lifetime risk for people who do not have a close relative with NHL is about 2 in 100 (2%).

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