© 2005-2012 American Society of Clinical Oncology (ASCO). All rights reserved worldwide.
A risk factor is anything that increases a person’s chance of developing cancer. Although risk factors often influence the development of cancer, most do not directly cause cancer. Some people with several risk factors never develop cancer, while others with no known risk factors do. However, knowing your risk factors and talking about them with your doctor may help you make more informed lifestyle and health care choices.
The exact cause of NHL is not known, but the following factors may raise a person’s risk of developing NHL:
Age. The risk of NHL increases with age. The most common types occur most often in people in their 60s and 70s.
Gender. Men are more likely to develop NHL than women.
Infections. Some types of NHL are associated with specific infections. For example, MALT lymphoma of the stomach is thought to be caused by an infection with bacteria called Helicobacter pylori. If this lymphoma is diagnosed very early, it will sometimes go away if the infection is cured with antibiotics. Other types of MALT lymphoma, including those affecting the lungs and the tear glands, may also be caused by infections.
Viruses. Viruses cause some types of NHL. For example, as explained in Subtypes, EBV is associated with some types of NHL, including Burkitt lymphoma and lymphomas occurring after organ transplantations. EBV may also cause some types of NHL in people between 60 to 90 years old. However, the virus is probably not the only factor, so people who have had mono do not necessarily have an increased risk of developing NHL in the future. In addition, hepatitis C infection has been associated with an increased risk of marginal zone lymphomas (see Subtypes). Other viruses have also been found to be important in causing other, rare types of lymphoma.
Immune deficiency disorders. Immune system disorders, such as HIV/AIDS, increase the risk of NHL, especially the aggressive B-cell lymphomas.
Autoimmune disorders. People with autoimmune disorders, such as rheumatoid arthritis and Sjögren syndrome, have an increased risk of developing certain types of NHL. Also, some drugs used to treat autoimmune disorders may increase the risk of NHL.
Organ transplantation. Organ transplant recipients have a higher risk of NHL because of the drugs that must be taken to lower the immune system and protect the transplanted organ.
Previous cancer treatment. Previous treatment with certain drugs for other types of cancer may increase the risk of NHL.
Chemical exposure. Exposure to certain chemicals, such as pesticides and petrochemicals, may increase the risk of NHL.