The Link Between Rheumatoid Arthritis and Lymphoma
Having RA increases the risk of lymphoma. But for most, that risk appears quite small.
RA and Lymphoma: Measuring the Risk continued...
Some doctors, though, including Barton A. Kamen, MD, PhD, believe that severe RA may raise one's risk significantly more than the studies cited above say. Kamen is executive vice president and chief medical officer of the Leukemia & Lymphoma Society. He points out that around the time Burke was training for her 2006 triathlon, Swedish researchers announced that patients with the most severe disease activity from RA had a 70-fold increased risk for lymphoma compared with those with low severity. Having moderate-severity RA appeared to make a person about eight times more likely to develop lymphoma.
There is a very rare complication of RA called Felty's syndrome. It's defined by the presence of RA along with an enlarged spleen and an abnormally low white blood count. People with Felty's syndrome appear to be at an even higher risk of lymphoma.
Personal Risk of Lymphoma Still Quite Small
Lymphoma is rare. It's estimated that fewer than 75,000 Americans were diagnosed with the disease last year. And the rarer a disease is, the lower the personal risk.
Rheumatologist Chaim Putterman, MD, explains it this way: "Say the risk for developing a disease is 1 in 10 million. If you have a twofold increased risk, your risk is now 1 in 5 million. That would be a very small increase in your own personal risk." Putterman is chief of the division of rheumatology and professor of medicine, microbiology, and immunology at the Montefiore Medical Center and Albert Einstein College of Medicine in New York.
There are two general types of lymphoma: Hodgkin's and non-Hodgkin's lymphoma (NHL). NHL is more common. One study published in January 2009 showed that RA is associated with increased risk for a subtype of NHL called diffuse large B-cell lymphoma. That's a fast-growing form of the disease. It also found an increased risk for a rarer subtype called T-cell lymphoma.
The actual risk may be related to how long a patient is treated for RA. In other words, the longer a person's immune system is suppressed, the greater the risk of lymphoma seems to be.