Background: Conventional synthetic disease-modifying antirheumatic drugs (csDMARDs) are recommended as first line treatment for rheumatoid arthritis (RA) patients, but limited information exists on the comparative risk of cancer associated with their use.

Objectives: To compare the risk of incident overall (excluding non-melanoma skin) and site-specific cancers (colorectal, lung, lymphoma, leukaemia) associated with first-line use of csDMARDs in patients with RA.

Methods: We conducted a multinational cohort study informed by data from 7 healthcare databases including claims and electronic medical records from 4 countries (SIDIAP-Spain, MDCR-US Optum-US, CCAE-US, IQVIA AMBEMR-US, IQVIA-Germany, THIN-UK) part of the Observational Health Data Sciences and Informatics (OHDSI) network. All patients aged ≥18 years who initiated methotrexate (MTX), hydroxychloroquine (HCQ), sulphasalazine (SSZ), or leflunomide (LEF) as first-line monotherapy after a diagnosis of RA between 2005 to 2018 were eligible. Individuals with a prior diagnosis of another inflammatory arthropathy or cancer, or <1 year of follow-up were excluded. Patients were followed from 1-year after treatment initiation to the earliest of incident cancer, loss to follow-up, or 5-years. Cox proportional-hazard models for MTX against each other csDMARD were performed after propensity score stratification. A large set of negative control outcomes were analysed to calibrate hazard ratios (cHRs). Estimates were pooled where homogeneity across sources was adequate (I ² <0.4).

Results: Across the databases, 127,547 RA patients initiating csDMARD therapy were included in the analyses (MTX: 73,996, HCL: 36,381 SSZ: 9,383 LEF: 7,787). The pooled incidence rate of overall cancer for MTX was 22.8 per 1,000 person years. The pooled summary and source-specific estimated cHRs for overall cancer are shown below in Figure 1 . While little difference was seen for HCQ and SSZ compared to MTX, LEF was consistently associated with a reduced cancer risk: pooled cHR (95% CI) 0.67 (0.59 to 0.76) and cHRs ranged from 0.53 (0.36 to 0.80) in CCAE-US to 0.84 (0.58 to 1.22) in SIDIAP-Spain. There were insufficient cases to look site-specific cancers within data sources, although pooled results suggest little risk difference in leukemia, lymphoma, colorectal, or lung cancers.

Figure 1.

Calibrated hazard ratios (cHRs) of overall cancer risk with their respective confidence intervals (95%CI) by study database. Database estimates not reported where adequate covariate balance not attained. Meta-analysis results not reported where I2>0.4.

Conclusion: Compared to MTX users, patients treated with LEF had a lower risk of overall cancer. Risk of four specific cancers did not differ by first line csDMARD exposure.

Disclosure of Interests : Talita Duarte-Salles: None declared, Martina Recalde: None declared, James Weaver Shareholder of: J&J Shares, Grant/research support from: Full-time employment salary from Janssen, Consultant of: Janssen employee, Employee of: Janssen, Paid instructor for: Janssen employee, have instructed at conferences, Speakers bureau: Janssen employee, have spoken at conferences, Edward Burn: None declared, Karine Marinier Employee of: Servier, Yesika Díaz: None declared, Ben Illingens: None declared, David Vizcaya Employee of: Bayer, Katerina Chatzidionysiou Consultant of: AbbVie, Pfizer, Lilly., Patrick Ryan: None declared, Daniel Prieto-Alhambra Grant/research support from: Professor Prieto-Alhambra has received research Grants from AMGEN, UCB Biopharma and Les Laboratoires Servier, Consultant of: DPA’s department has received fees for consultancy services from UCB Biopharma, Speakers bureau: DPA’s department has received fees for speaker and advisory board membership services from Amgen