Circulating levels of cytokines and risk of urologic cancers: a two-sample Mendelian randomization study.

Background: Chronic inflammation is associated with the etiology of various cancers. However, there is a lack of systematic research in urologic cancers. This study aims to use a two-sample Mendelian randomization (MR) approach to evaluate the role of circulating cytokines in the development of urologic cancers.

Methods: We obtained the summary-level data for bladder cancer (373,295 cases and 372,016 controls), prostate cancer (462,933 cases and 459,664 controls), and kidney cancer (463,010 cases and 461,896 controls) from the UK Biobank. Genetic variations linked to 41 circulating cytokines were used as instrumental variables (IVs) in meta-analyses of genome-wide association studies (GWASs) involving 8,293 individuals from Finland. We primarily used the inverse-variance weighted (IVW) method to assess the potential associations between the 41 cytokines and the risk of 3 common urologic cancers. Weighted-median method, weighted mode and simple-median method were used to assess the sensitivity. Heterogeneity and pleiotropic outlier were evaluated by Cochran's Q test and MR-Egger regression. Genetic correlation, colocalization analysis and multivariable MR analysis were used to further validate the potential pleiotropy.

Results: After the Bonferroni correction, there was an observed association between elevated genetically predicted levels of CCL27 and a heightened risk for bladder cancer. Conversely, IL-12p70 levels were found to have a protective association against the risk of bladder cancer. Sensitivity analyses utilizing various IV sets and MR approach remained robust. Furthermore, we found potential associations of 7 cytokines with urologic cancers (4.07 × 10^-4 ≤ P < 0.05).

Conclusion: Our study supported causal associations between CCL27, IL-12p70 and bladder cancer risk and potential associations of 7 cytokines with the risk of urologic cancers, helping us to further understand the pathogenesis of urologic cancers and providing clues for improving diagnostic accuracy and therapies.