Several studies show an increased risk of cancer, particularly non-Hodgkin's leukemia, in patients with systemic lupus erythematosus.
Several studies, including several that were presented at the Sixth Annual European Lupus Meeting in London in March 2005, suggest that patients with systemic lupus erythematosus (SLE) have an increased risk of developing cancer and related malignancies. The reasons for this increased risk are unclear. However, studies show that the use of corticosteroids and other immunosuppressants in patients with systemic lupus erythematosus does not cause an increased risk for cancer although, for reasons that are uncertain, these medications are associated with a higher risk for cancer in patients with rheumatoid arthritis.
Types of Cancer
Patients with systemic lupus erythematosus have an especially high risk for non-Hodgkin’s lymphoma, lung cancer, liver cancer, ovarian cancer, breast cancer, and cancer of the bile ducts. An increase in cervical dysplasia, a precursor of cervical cancer, has also been reported in females with SLE suggesting a link between the human papillomavirus (HPV), which causes most cervical cancer, and the development of systemic lupus erythematosus. In one study, patients with lupus also had a significantly increased risk of developing skin cancer.
Risk Factors
Although corticosteroids are not suspected of increasing the risk of cancer in lupus patients, studies have shown that long-term use of intravenous cyclophosphamide is associated with a higher cancer risk, particularly of bladder cancer and cervical cancer. Researchers suspect that the immunosuppression caused by cyclophosphamide increases the risk for developing HPV infection.
In addition, the genetic factors and immune system changes that predispose patients to developing systemic lupus may increase their risk of developing cancer. A low population of Th1 suppressor lymphocytes, which is seen in lupus and other autoimmune disorders, causes an increased risk for cancer.
Synthetic estrogens, such as Premarin, used as a form of hormone replacement therapy are also reported to increase the risk of SLE and gallbladder cancer. More information can be found at the Injured by Premarin? Website.
Other suspected triggers of both cancer and systemic lupus include hazardous industrial waste, pesticides, fungicides and chemical solvents.
Autoantibodies
Various autoantibodies are seen in both lupus and in malignancies. These include autoantibodies to proliferating nuclear cell antigen (PNCA), autoantibodies to p53, and autoantibodies to tumor-associated antigens (TTA) in cancer, and autoantibodies to nuclear antigens in systemic lupus erythematosus. The mechanism of autoantibody production, which is related to a disruption of B cell activity, is similar in both types of disease.
Resources
C. Gordon, Long-term complications of systemic lupus erythematosus, Rheumatology 2002; 41: 1095-1100.
Janis Kelly, IV cyclophosphamide raises cervical-cancer risk in lupus patients, Medscape Medical News, Sept 2004.
Tam LS, Chan AY, Chan PK, Chang AR, Li EK. Increased prevalence of squamous intraepithelial lesions in systemic lupus erythematosus: association with human Papillomavirus infection. Arthritis Rheum 2004 Nov;50(11): 3619-25.
