Risk factors

Most people diagnosed with non-Hodgkin's lymphoma don't have any obvious risk factors. And many people who have risk factors for the disease never develop it.

Some factors that may increase the risk of non-Hodgkin's lymphoma include:

• Medications that suppress your immune system. If you've had an organ transplant and take medicines that control your immune system, you might have an increased risk of non-Hodgkin's lymphoma.
• Infection with certain viruses and bacteria. Certain viral and bacterial infections appear to increase the risk of non-Hodgkin's lymphoma. Viruses linked to this type of cancer include HIV and Epstein-Barr infection. Bacteria linked to non-Hodgkin's lymphoma include the ulcer-causing Helicobacter pylori.
• Chemicals. Certain chemicals, such as those used to kill insects and weeds, may increase your risk of developing non-Hodgkin's lymphoma. More research is needed to understand the possible link between pesticides and the development of non-Hodgkin's lymphoma.
• Older age. Non-Hodgkin's lymphoma can occur at any age, but the risk increases with age. It's most common in people 60 or over.