Non-Hodgkin's Lymphoma - Risk Factors

(Page 3)

Smoking. There is no evidence that smoking increases the risk for NHL itself, although it has been linked with high-grade and follicular NHLs in people with lymphomas.

Infections

Viruses or other microorganisms also play a role in some lymphomas. A number are being investigated:

• Epstein-Barr virus, the cause of mononucleosis, is highly associated with Burkitt's disease and NHLs associated with immunodeficiency diseases. It is also a risk factor for Hodgkin's disease
• Adult T-cell leukemia-lymphoma, which appears to be caused by a virus known as HTLV-I, has been found in southwestern Japan, the Caribbean, and the southeastern United States.
• People who have stomach inflammation due to Helicobacter pylori or H. heilmannii bacteria are at increased risk for mucosa-associated lymphoid tissue lymphomas (MALT). (The use of antibiotics to get rid of the bacteria may cause remission in some patients who have an early stage form of lymphoma in an early stage.)
• Human herpesvirus 8 has been associated with NHL.
• Borrelia burgdorferi, the bacteria that causes Lyme disease, has been associated with primary B-cell lymphoma.
• Heavy antibiotic use during adulthood may increase risk. A 2005 study found that adults who used antibiotics more than 10 times had 1.8 times the risk of developing NHL than nonusers. However, researchers were not certain if antibiotics themselves, or the underlying infections they treated, were responsible for the increased risk.

Click the icon to see an image of Lyme disease.

Studies are reporting a higher prevalence of viral hepatitis C and B in patients with lymphomas, although such viruses do not appear to play a major role in triggering lymphoma.

One study reported a lower risk for certain lymphomas in people with a history of receiving five or more different vaccines.

Disorders of the Immune System

Patients with diseases or conditions that affect the immune system may be at higher risk for lymphomas:

• HIV-positive patients and those with full-blown AIDS are at higher risk for NHL, and the disease is more likely to be widespread in these patients than in those without the immune disease. Most AIDS-related NHLs are high-grade lymphomas. Burkitt's lymphoma is often seen in patients with AIDS. Although these patients have had a very poor prognosis, advances in antiviral therapy for HIV now allow better management of NHL with some success in achieving favorable outcomes. Part of the dramatic increase in NHL incidence over the past decades can, in fact, be traced to AIDS. However, one 2002 study observed that AIDS is now declining in the U.S., but non-AIDS-related NHL continues to increase.
• Patients with a history of autoimmune diseases, including rheumatoid arthritis (RA), Hashimoto's thyroiditis, Crohn's disease, and Sjögren syndrome are at an increased risk for certain NHLs, such as marginal zone lymphomas. [See section: Other Conditions Associated with Non-Hodgkin's Lymphomas.]
• People who have organ transplants are at higher risk for NHL, probably due to multiple factors, including the drugs used to suppress the immune system and the transplanted organ itself.
• Patients who have had high-dose chemotherapy with stem-cell transplantation are at higher risk.
• Other immunodeficiency syndromes that put people at risk for NHL include Chediak-Higashi syndrome, ataxia-telangiectasia, B-cell lymphoproliferative syndrome, Bruton agammaglobulinemia, common variable immunodeficiency, and Wiskott-Aldrich syndrome.