medwireNews: Treatment with biologic DMARDs does not elevate the risk for lymphoma among patients with rheumatoid arthritis (RA), report researchers from the ARTIS study group.
“[B]y contrast, such treatment seems currently associated with lower rather than higher lymphoma risks in RA,” say Karin Hellgren (Karolinska Institutet, Stockholm, Sweden) and team, noting that “patients with RA have about a doubled risk of malignant lymphoma compared with the general population.”
The Swedish registry study involved 16,392 RA patients who initiated treatment with a biologic DMARD in 2001–2016, 55,253 RA patients who did not receive biologics over the same period, and 229,047 non-RA controls matched for factors including age, sex, and geographic location.
During a median follow-up of 7.4 years, 82 biologic-treated patients developed incident lymphoma, as did 310 RA patients without biologic exposure. These findings translated into a numerically lower crude incidence rate in the biologics group (76 vs 90 per 100,000 person–years), but the between-group difference did not reach statistical significance in a model adjusting for sex, age, education level, and comorbidities.
On the other hand, there were “signals of a reduction of the excess lymphoma risk in association with [biologic] DMARDs” when the analysis was restricted to the follow-up period from 2006 onwards, say Hellgren and team.
During this time, the incidence rate of lymphoma was 32 per 55,440 person–years for biologic-treated patients, compared with 232 per 261,951 person–years for biologic-naïve RA patients, giving an adjusted hazard ratio (HR) of 0.69 (95% confidence intervals 0.47, 1.00).
These findings “provide some support of a decline in lymphoma risk in [biologic] DMARD-treated vs [biologic] DMARD-naïve RA patients over successive calendar periods,” write the researchers in Rheumatology.
“It may be that [biologic] DMARDs, by lowering the RA disease activity, may in fact modify the excess lymphoma risk in RA, and that we now, after sufficiently long follow-up periods, can observe the first evidence of such a risk reduction,” they add.
The study authors also evaluated lymphoma risk in subgroups of patients according to the type of biologic, finding “no signs of increased risk” associated with individual agents. Moreover, there were no significant differences in the risk for lymphoma among biologic-treated versus biologic-naïve RA patients when different lymphoma subtypes were analyzed separately.
In accordance with previous studies, both biologic-treated and biologic-naïve RA patients had a significantly higher risk for lymphoma compared with those in the general population, with adjusted HRs of 1.65 and 1.56, respectively.
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