Do JIA Patients Have An Increased Cancer Risk?

A newly published study examined trends in the risk of cancer among patients with juvenile idiopathic arthritis (JIA).

“Biologic disease-modifying antirheumatic drugs (bDMARDs) such as tumour necrosis factor inhibitors have revolutionised the treatment of JIA. Ever since the initial approval of bDMARDs, there have been concerns about a potential increased risk of malignancy,” the reserchers explained, adding, “Although the safety profile of bDMARDs is generally well understood, some worries remain. For instance, fear of long-term cancer risk is one reason that patients (or their parents and prescribers) are reluctant to try what may otherwise be both a needed and effective therapy.”

The researchers used the Swedish Patient Register to identify data on JIA patients spanning 2001 through 2017; JIA patients were matched 1:5 to non-JIA controls. All patients were followed up for incident cancers until they turned 18 years old or until Dec. 31, 2016.

Final analysis included 6,721 JIA patients; of these patients, 10 incident malignancies were identified during 34,951 person-years of follow-up. The 10 incident malignancies included five lymphoproliferative cancers. In the matched cohort, during 174,529 person-years of follow-up, 35 incident malignancies were identified, of which seven were lymphoproliferative cancers, totaling “an excess incidence of 0.09 cancers per 1000 person-years in the JIA population (one extra case per 11 000 patients per year), an HR [hazard ratio] for all-site cancer of 1.4 (95% CI 0.7 to 2.9), an HR for lymphoproliferative malignancies of 3.6 (95% CI 1.1 to 11.2), and an HR for all sites but lymphoproliferative cancers of 0.89 (95% CI 0.34 to 2.31),” the researchers observed.

When the follow-up time was extended to include all available ages, the JIA follow-up time totaled 55,107 person-years, during which time 18 incident JIA cancers occurred; the HRs for all cancers and lymphoproliferative cancers were 1.1 and 3.2, respectively. Other adjustments did not significantly change these outcomes.

Among patients still in the study in 2006 and who were followed until they turned 18, 32% (n = 2,037) had at least one subcutaneous bDMARD treatment recorded; among patients still in the study in 2015, this increased to 52%. Six JIA patients received a cancer diagnosis in 2006 or later, of whom one patient had a recorded bDMARD treatment during follow-up.

The study appeared in RMD Open.

“In summary, our study showed that patients with JIA are at increased risk of developing malignant lymphoma compared with the general population, but the absolute risk is very low,” the researchers concluded. “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. This apparent absence of risk should be reassuring for both prescribers and patients/their parents.”