Risk of malignancy in patients with rheumatoid arthritis after anti-tumor necrosis factor therapy: results from Korean National Health Insurance claims data

Background/Aims: Inhibition of tumor necrosis factor (TNF) is an effective treatment for rheumatoid arthritis (RA), but safety concerns about malignancy remain. The aim of this study was to evaluate cancer risk in RA patients treated with TNF inhibitors (TNFi), based on Korean Nationwide Health Insurance claims data. Methods: Patients with seropositive RA were selected from the health insurance database containing all citizens' medical information, based on both RA diagnosis codes and medications. Between 2010 and 2014, RA patients treated with conventional synthetic disease-modifying anti-rheumatic drugs (csDMARDs) and TNFi were enrolled and followed up. We compared the cancer incidence between patients treated with TNFi and csDMARDs using incidence rate ratios (IRRs) after adjustment for age, gender, and observational periods. Results: Of 45,423 selected patients with seropositive RA, 2,337 were treated with TNFi and 43,086 were treated with csDMARDs. The TNFi group was younger and was followed-up for a longer duration. During the observational period, 1,732 and 49 cases of cancer were detected in patients treated with csDMARDs and TNFi, respectively. Old age and male sex were associated with cancer occurrence. Adjusted IRRs for all cancers and common cancers demonstrated that cancer incidence did not differ significantly between the TNFi group and csDMARDs group (IRR = 0.913 for all cancers, p = 0.546). Conclusions: This study revealed that cancer incidence was similar in RA patients treated with TNFi and csDMARDs. Anti-TNF therapy may be a safe therapeutic option for RA treatment, in terms of malignancy.