Associations between rheumatoid arthritis and skin cancer: A bidirectional two-sample Mendelian randomization study.

Chronic inflammation has the capacity to induce gene mutations and DNA damage, which can lead to tumorigenesis. Consequently, the relationship between chronic inflammatory diseases and tumors is a subject of significant interest in research. Rheumatoid arthritis (RA), as a chronic autoimmune inflammatory disease, has established the relationship between RA, biologic disease-modifying antirheumatic drugs (bDMARDs), and skin cancer.Observational studies have indicated that the utilization of bDMARDs in RA could elevate the risk of non-melanoma skin cancer (NMSC). However, the precise factors responsible for the increased risk of skin cancer remain unknown. Mendelian randomization (MR) employs genetic variation as a natural experiment to study associations between exposure and outcome, with the advantage of being less likely to be affected by confounding factors or reverse causation than observational studies. Here, we conducted a bidirectional MR analysis to investigate the associations between RA and skin cancer.