The risk of malignancy and its incidence in early rheumatoid arthritis patients treated with biologic DMARDs

Background: Treatment with disease-modifying anti-rheumatic drugs (DMARDs) has raised concerns about the risk of malignancies in rheumatoid arthritis (RA) patients. However, the association between biologic DMARDs (bDMARDs) and malignancy in previous reports remains controversial. Therefore we aimed to estimate the incidence of malignancy in early RA patients and to evaluate the relative risk of malignancy with use of bDMARDs. Methods: A retrospective cohort of incident RA patients was established using the Korean National Claims Database. Among a total of 14,081 RA patients identified, 1684 patients with a history of malignancy were excluded. We calculated the incidence rate of overall and individual malignancies. The standardized incidence ratio (SIR) of malignancies in bDMARD users was compared to that in nonusers. Multivariable logistic regression analysis was used to evaluate the impact of bDMARDs on the development of malignancies in early RA patients. Results: A total of 12,397 early RA patients without a history of malignancy were enrolled. During 41,599 person-years (PY) of follow-up, 725 malignancies developed in 561 patients (174.3/10,000 PY) and 21 hematologic malignancies developed (5.0/10,000 PY). Patients treated with bDMARDs had a significantly lower incidence of overall malignancy compared to those not treated with bDMARDs (SIR 0.45 (95% CI 0.28-0.70)). However, this relationship was not significant with regard to hematologic malignancies (SIR 2.65 (95% CI 0.55-7.76)). On multivariable analysis, bDMARD use was a protective factor against the development of overall malignancy (odds ratio 0.42 (95% CI 0.25-0.73)). However, bDMARD use had no significant protective effect against the development of hematologic malignancies (odds ratio 1.69 (95% CI 0.38-7.59)). Conclusions: In early RA patients, bDMARD use decreases the overall risk of developing malignancies; however, it does not affect the risk of developing hematologic malignancies.