# Causal Association Between Oral Microbiota and Major Salivary Gland Cancer: A Bidirectional Two-Sample Mendelian Randomization Study

## TL;DR

This study finds a causal link between two oral microbes and an increased risk of major salivary gland cancer using genetic data.

## Contribution

The study identifies specific oral microbes with a causal relationship to major salivary gland cancer using Mendelian randomization.

## Key findings

- Alloprevotella genus increases the risk of major salivary gland cancer (OR = 1.267).
- Veillonella dispar species increases the risk of major salivary gland cancer (OR = 1.369).
- Causal relationships were confirmed using multiple robustness checks like Cochran’s Q and MR-Egger tests.

## Abstract

The two-sample Mendelian randomization approach was used to assess the potential causal relationships between 33 oral microbes and salivary gland cancer.

The data used in this study were obtained from summary statistics of genome-wide association studies (GWAS). The instrumental variables included 33 known oral microbes, comprising a total of 39,117,105 single nucleotide polymorphisms (SNPs). The outcome variable, major salivary gland cancer (MSGC), included 11,831,294 SNPs. Mendelian randomization (MR) analysis was conducted via inverse-variance weighted (IVW) as the primary method. To ensure the robustness of the results, Cochran’s Q test, the MR-Egger intercept test, leave-one-out analysis, and reverse MR analysis were employed.

The IVW analysis results indicated that the genus Alloprevotella (odds ratio [OR] = 1.267; 95% confidence interval (CI) = 1.037–1.549; p = 0.020) and the species Veillonella dispar (OR = 1.369; 95%CI = 1.081–1.734; p = 0.009) are statistically significant risk factors for the occurrence of MSGC.

The genus Alloprevotella and the species Veillonella dispar have a positive causal relationship with major salivary gland cancer.