In recent years, the worldwide incidence of malignant lymphoma has increased dramatically, and the number of autoimmune diseases linked to non-Hodgkin’s lymphoma (NHL) has also increased. In the United States, non-Hodgkin’s lymphoma is listed as the 5th most commonly diagnosed cancer. In an attempt to determine if the increased risk for malignant lymphoma occurs in all chronic inflammatory and autoimmune disorders, Swedish researchers have conducted a study of available data.
What is Lymphoma?
Lymphoma is a general term for a family of cancers that originate in the lymphatic system. Lymphoma is caused by an increased proliferation of white blood cells known as lymphocytes. While both T and B lymphocytes can be affected by lymphoma, about 85 percent of all lymphomas originate in B lymphocytes.
Lymphoma has two major subtypes: Hodgkin’s lymphoma and non-Hodgkin’s lymphoma. Non-Hodgkin’s lymphoma is nearly 9 times more prevalent than Hodgkin’s lymphoma and it affects males slightly more often than females. In the United States, it’s expected that about 68,000 new cases of non-Hodgkin’s lymphoma will be diagnosed in 2008.
Lymphoma usually starts in lymph nodes or in clusters of lymphatic tissue, for instance lymphatic tissue lining the stomach or intestines. Lymphoma may also involve lymphocytes in the bone marrow and the blood, and it may spread from one site to other parts of the body.
Symptoms in NHL vary depending on the tissue affected and include unexplained weight loss, night sweats, fever, swollen lymph nodes, and abdominal bloating.
Autoimmune Disorders Associated with Lymphoma
Swedish researchers found that NHL is most likely to develop in individuals with severe autoimmune disease, particularly during the first year following diagnosis. An increased occurrence of lymphoma in the following conditions:
- Rheumatoid arthritis, especially patients with Felty’s syndrome
- Sjogren’s syndrome, especially primary disease
- Systemic lupus erythematosus (SLE)
- Celiac disease, especially in patients with co-existing autoimmune disorders
- Dermatitis herpetiformis
- Chronic thyroiditis, particularly an increase risk for thyroid lymphoma
- Polymyositis
- Dermatomyositis
- Inflammatory Bowel Disease, particularly ulcerative colitis
- Psoriasis and Spondyloarthropathies, particularly T-cell lymphoma and mycosis fungoides
Environmental Causes of Lymphoma
In addition to the link with autoimmune and inflammatory disorders, several environmental factors have been found to increase the risk of developing lymphoma. The Epstein-Barr virus (EBV) has a strong association with lymphoma, particularly Burkitt’s lymphoma. Organ transplantation, the human immunodeficiency virus (HIV) and the HTLV virus are also associated with an increased risk of lymphoma. Because viruses are also known to trigger certain autoimmune diseases, the viral link is of particular interest to researchers.
Studies have also shown increased levels of polychlorinated biphenyl compounds (PCBs), organochlorines, furans and dioxins in some patients with non-Hodgkin’s lymphoma. These chemicals are found in industrial waste, waste incineration, and pesticides.
Resources:
Karin Ekstrom Smedby, Eva Baecklund, and Johan Askling, Malignant Lymphomas in Autoimmunity and Inflammation: A Review of Risks, Risk Factors, and Lymphoma Characteristics, Cancer Epidemiology Biomarkers and Prevention, Nov 2006; 15;110: 2069-77.
Cancer and Chemical Exposure, Research Notes, Fred Hutchinson Cancer Research Center, Spring, 2006.
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