However, this higher risk is not associated with an increased use of biological disease-modifying antirheumatic drugs (bDMARDs), the research also found.
The study, “Juvenile idiopathic arthritis and risk of cancer before and after the introduction of biological therapies,” was published in the journal RMD Open.
In recent years, DMARDs has become the standard first-line therapy for children and adolescents with JIA. Their use has raised concerns about a potential higher risk of cancer, but conclusions have not been drawn due to factors such as the small number of JIA patients in existing studies, the low incidence of cancer in children, and the possibility that cancer risk may be due to the disease itself rather than the therapy.
Therefore, researchers from the Karolinska Institutet, in Sweden, decided to investigate the possible link between cancer and the recent increased use of bDMARDs in children and adolescents with JIA.
To that end, they analyzed data from 6,721 JIA patients who were identified through the Swedish Patient Register. Each patient was matched to five individuals from the general Swedish population of the same age and sex who did not have the disease (controls).
Using the Swedish Cancer Register, patients and controls were monitored for incident cancers until they reached the age of 18 or until the end of 2016.
Results showed 10 cancer cases in the JIA group between 2001 and 2016. Half of those who had cancer were diagnosed with lymphoproliferative cancer, a type of malignancy that leads to the abnormal growth of cells forming the lymphatic system.
In the control group, 35 individuals had cancer within the same period of time, including seven with lymphoproliferative cancer. After comparing the two groups, the researchers found that those with JIA had a slightly higher risk of having cancer compared to those who did not have the disease.
“In this study of almost 7,000 Swedish patients with JIA, we confirm that the risk for patients with JIA to develop cancer is low, with one extra case of cancer per every 11,000 patients per year,” the researchers wrote.
Specifically, those with JIA were 1.4-times more likely to have cancer than the general population. This risk increased to 3.6 times when considering lymphoproliferative malignancies such as Hodgkin’s and non-Hodgkin’s lymphoma, lymphocytic leukemia, and multiple myeloma.
However, when researchers looked at the rates of cancer over time, they did not find an increase in recent years that would correspond with the introduction of bDMARDs. This suggests that the slightly higher incidence of cancer in people with JIA is unrelated to treatment with these agents.
“There is no sign that the risk of cancer in patients with JIA has been increasing over the past 20 years, during which time treatment with bDMARDs has become common,” the researchers said. “This apparent absence of risk should be reassuring for both prescribers and patients/their parents.”
However, cancer in people with JIA “should be monitored continuously to provide longer-term risk assessment,” the researchers added.