An increased risk of lymphoma has been associated with rheumatoid arthritis (RA). Various studies have linked the two conditions but it has never been completely clear whether disease activity or the treatments used to battle rheumatoid arthritis cause the increased risk of lymphoma.
Researchers Seek Answers To Lymphoma Risk For Rheumatoid Arthritis Patients
Lymphoma is cancer of the lymphatic system (lymph nodes, spleen, and other organs of the immune system). The connection between an increased risk of lymphoma in rheumatoid arthritis patients concerns researchers, doctors, and patients. Unanswered questions remain:
Researchers In Sweden Conduct Large Study
Researchers in Sweden have conducted the largest study to date in an attempt to find answers to these questions. Researchers obtained the medical records and histories of 378 rheumatoid arthritis patients who developed malignant lymphoma between 1964 and 1995.
The patients were selected from a national register of 75,000 rheumatoid arthritis patients. The 378 rheumatoid arthritis patients who had malignant lymphoma were matched to 378 rheumatoid arthritis patients who served as lymphoma-free controls.
Using statistical analysis the relative risks or odds ratios for lymphoma were assessed for low, medium, or high disease activity associated with rheumatoid arthritis. Disease activity was based on duration of disease and swollen and tender joint counts. Odds ratios were assessed for the following treatment categories:
- DMARDs (disease-modifying anti-rheumatic drugs)
- NSAIDs (nonsteroidal anti-inflammatory drugs)
- oral corticosteroids
- injected steroids
- cytotoxic drugs
No patient in the study had ever been on an anti-TNF drug, such as:
Lymphoma patients in the study were also tested for Epstein-Barr virus.
Lymphoma Study Results
Lymphoma Study - Conclusion
Researchers concluded that patients with very severe rheumatoid arthritis who have prolonged, active inflammation are at the highest risk for developing lymphoma. Chronic inflammation and not the anti-inflammatory treatments appear to be connected to lymphoma risk in rheumatoid arthritis patients. Early, aggressive treatment to control inflammation is obviously important.
Sources: "New insights into the link between rheumatoid arthritis and cancer" EurekAlert; Arthritis & Rheumatism, March 2006