The Association Between Melanoma and Autoimmune Diseases: A Nationwide Population-Based Study in the Republic of Korea.

Few population-based studies have investigated the association between melanoma and autoimmune diseases in Asian populations. We conducted a population-based cross-sectional study using the South Korean National Health Insurance database to investigate the association between melanoma and autoimmune diseases in Asian individuals. Melanoma patients were identified, and birth year and sex matched controls were randomly selected at a 1:10 ratio. Multivariable logistic regression was used to evaluate the association between melanoma and autoimmune diseases. The study involved 12 040 melanoma patients and 120 400 matched controls. Melanoma patients had significantly higher odds of vitiligo (adjusted odds ratio [aOR], 4.05; 95% confidence interval [CI], 3.38-4.85), ulcerative colitis (aOR, 1.81; 95% CI, 1.24-2.62), psoriasis (aOR, 1.54; 95% CI, 1.32-1.79), Hashimoto's thyroiditis (aOR, 1.50; 95% CI, 1.21-1.85), ankylosing spondylitis (aOR, 1.42; 95% CI, 1.06-1.91), and type 1 diabetes mellitus (aOR, 1.27; 95% CI, 1.08-1.49). Most autoimmune diseases showed a stronger association with melanoma in younger individuals (aged 20-60 years) compared to older individuals (aged > 60 years). In conclusion, melanoma was significantly associated with several autoimmune diseases, suggesting shared pathophysiological mechanisms.