Investigating the causal association between liver condition and melanoma: evidence from the National Health and Nutrition Examination Survey and Mendelian randomization.
This study aimed to investigate the association between liver condition and the risk of melanoma. We first conducted a cross-sectional study using data from the National Health and Nutrition Examination Survey (NHANES) 2001 to 2004, involving 7144 participants (49 melanoma cases). The association was examined using multivariable logistic regression (three models), smooth curve fitting, and stratified analysis. To infer causality, a Mendelian randomization analysis was then performed using five algorithms, with sensitivity analyses and a Steiger test to validate the findings. In the NHANES analysis, liver condition was significantly associated with an increased risk of melanoma across all models [model 3: odds ratio (OR) = 4.31, 95% confidence interval (CI): 1.47-12.7]. The Mendelian randomization analysis using the inverse variance weighted method confirmed a positive causal relationship, identifying liver condition as a risk factor for melanoma (OR = 1.173, 95% CI: 1.051-1.310). Sensitivity analyses indicated no heterogeneity or horizontal pleiotropy, and the Steiger test supported the direction of causality. This study suggests a causal association between liver condition and melanoma, offering new insights for the prevention and treatment of melanoma.