Is there a causal relationship between autoimmune diseases and oropharyngeal cancer?

Background: Autoimmune diseases (AIDs) are linked to oropharyngeal cancer (OPC), but the exact nature of this association remains unclear. This study aims to examine the potential causal effect of AIDs on the risk of developing OPC. Method: Information regarding AIDs was collected from the UK Biobank dataset and the Finn Gen study. OPC data were sourced from the IEU Open GWAS project. All data were derived from European populations. Inverse variance weighted (IVW) to two-sample Mendelian randomization (MR) was complemented by weighted median and MR Egger validation analyses. Result: The development of asthma (AS), multiple sclerosis (MS), and rheumatoid arthritis (RA) influenced the risk of developing OPC. However, the reverse MR analysis did not provide evidence for the impact of OPC on AIDs. Sensitivity analysis using MR corroborated the IVW results. The IVW results indicate OR values of 1.004 for AS, 0.936 for MS, and 1.0002 for RA. Conclusion: This MR study supports a causal relationship between asthma and rheumatoid arthritis for OPC in a European population. Multiple sclerosis was protective against OPC.