MCGILL (CAN) — Taking medication to treat lupus does not significantly increase the risk of lymphoma, according to new research.
The study, which is published in Annals of the Rheumatic Diseases this month, addresses long-standing fears of a link between taking immunosuppressive drugs to treat lupus and cancer.
Systemic lupus erythematosus (SLE), commonly known as lupus, is an autoimmune disease in which the body’s immune system attacks healthy tissue such as the skin, joints, kidneys, and the brain, leading to inflammation and lesions.
The disease affects about 1 in 2000 Canadians, particularly women. Previous research has suggested that lupus patients have an increased risk of developing cancer, particularly lymphoma. Lymphoma is a type of blood cancer that occurs when cells called lymphocytes, which usually help protect the body from infection and disease, begin growing and multiplying uncontrollably leading to tumor growth.
“Treatment for Lupus consists largely of immunosuppressive medications, which lower the body’s immune response,” explains Sasha Bernatsky, first and corresponding author of the study, who is a researcher within the Divisions of Clinical Epidemiology and Rheumatology at the Research Institute of the McGill University Health Centre and at McGill University.
According to Ann E. Clarke, director of the lupus clinic and co-leader of the study, the fear of developing cancer among lupus patients has been so great that some were reluctant to take their medication and other stopped altogether.
The international study involved 75 lupus patients with lymphoma from different centers around the world and nearly 5,000 cancer-free lupus patients as a control. Researchers studied most of the drugs commonly used to treat SLE including cyclophosphamide, a drug reserved for severe lupus cases and other chronic inflammatory rheumatic diseases.
The results showed that the risk for lymphoma in lupus patients exposed to cyclophosphamide was less than 0.1 percent per year. In addition, no clear association was observed between lupus disease activity and lymphoma risk.
“People have been wondering for a long time whether the medications were to blame and the results are reassuring, suggesting that most lymphoma cases in SLE are not triggered by drug exposures,” says Bernatsky.
“This is very good news that cancer risk associated with lupus medication is relatively low,” says Louise Bergeron, who has been living with lupus for 12 years. “It reassures me, especially if I need to take more effective immunosuppressive treatments in the coming years.”
Future research will focus on the genetic profiles of lupus patients and what impact that can have on the interaction between medication exposure and lymphoma risk in lupus.
The Canadian Institutes of Health Research and the National Institutes of Health funded the study.
Source: McGill University