Causal validation of the relationship between air pollution and ovarian cancer: A bidirectional Mendelian randomization study and meta-analysis

In recent years, an increasing number of observational studies have reported the impact of air pollution on ovarian cancer. However, a Mendelian randomization (MR) study to explore the causal relationship in ovarian cancer has not yet been conducted. This study, based on 2-sample MR, conducts MR analysis by examining 5 air pollution indices with ovarian cancer data from 2 different sources. Subsequently, a meta-analysis of the primary inverse-variance weighted results is performed, followed by multiple corrections on the meta-analysis thresholds to ensure accuracy. Finally, a reverse causality verification of the positive air pollution indices with ovarian cancer is conducted through MR analysis. The MR analysis was conducted using 5 air pollution indices and ovarian cancer data from the Finngen R10 and OpenGWAS databases. A meta-analysis was then performed on the inverse-variance weighted results from both sets of analyses. Multiple corrections were applied to the significance threshold of the meta-analysis results, revealing an odds ratio value of 1.544 (95% confidence interval: 1.180-2.020, P = .0077). Additionally, the positive air pollution index, nitrogen dioxide, showed no reverse causality with ovarian cancer in both data sources. Nitrogen dioxide is a risk factor for ovarian cancer and may increase the risk, accelerating the onset and progression of the disease.