From autoimmune inflammation to malignancy: causal genetic evidence for the RA-squamous cell lung cancer axis

RA specifically increases squamous cell lung cancer (but not other subtypes) risk. Multivariable Mendelian randomization resolves the causal paradox caused by smoking confounding. Clinical evidence (China) and genetic evidence (Europe) come from different populations and require further validation. Results support implementation of targeted squamous cell lung cancer screening for high-risk RA patients.