Meta-Analysis of the Incidence and Influencing Factors of Malignant Tumors in Patients with Rheumatoid Arthritis.

PURPOSE: This study aims to systematically evaluate the incidence of malignant tumors in rheumatoid arthritis (RA) patients and identify influencing factors, providing an evidence-based foundation for early identification of high-risk groups and individualized management. METHODS: Cohort studies on tumor incidence and ifluencing factors in RA patients were searched in both Chinese and English databases from inception to July 31, 2025. Two researchers independently screened literature, extracted data, and assessed quality. Meta-analysis was performed using Stata 12.0 to calculate pooled incidence and hazard ratios (HR) with 95% confidence intervals (CI). The study is registered with Prospero (CRD420251141184). RESULTS: A total of 44 cohort studies involving 901,941 RA patients were included. The pooled incidence of malignant tumors was 4.1% (95%CI 3.3%-4.8%). Significant influencing factors were: age (HR 1.17, 95%CI 1.12-1.22), male sex (HR 1.58, 95%CI 1.23-2.04), smoking (HR 1.33, 95%CI 1.07-1.66), tumor necrosis factor inhibitor (TNFi) use (HR 0.80, 95%CI 0.66-0.97), abatacept use (HR 1.19, 95%CI 1.10-1.29), and comorbidities (HR 1.13, 95%CI 1.02-1.26), particularly lung disease (HR 2.17, 95%CI 1.48-3.17) and diabetes (HR 1.10, 95%CI 1.03-1.17). The following influencing factors without statistical significance are: body mass index(BMI), Non steroidal anti-inflammatory drugs(NSAIDs), methotrexate(MTX), biological disease-modifying antirheumatic drugs/targeted synthesis disease-modifying antirheumatic drugs(bDMARDs/tsDMARDs), interleukin-6 inhibitor(IL-6i), Janus kinase inhibitor(JAKi), glucocorticoid, serum-positive, diease duration. CONCLUSION: Among RA patients, older age, male sex, smoking, abatacept use, and comorbidities may be associated with increased tumor risk, while TNFi use may be associated with lower risk. Clinicians should consider these factors to identify high-risk populations for enhanced monitoring.