Genetic susceptibility association between viral infection and colorectal cancer risk: a two-sample Mendelian randomization analysis.

Background: The genetic susceptibility association between viral infection and the risk of colorectal cancer (CRC) has not been established.

Methods: We conducted two-sample Mendelian randomization (MR) analysis using genome-wide association study (GWAS) data. In addition to traditional MR methods, we employed several other approaches, including cML, ConMix, MR-RAPS, and dIVW, to comprehensively assess causal effects. Sensitivity analyses were also performed to ensure the robustness of the results.

Results: After sensitivity analysis, presence of SNPs linked to increased susceptibility to cold sores infection was found to decrease the risk of CRC (OR: 0.73, 95% CI: 0.57-0.93, P = 0.01). In subgroup analysis, presence of SNPs linked to increased susceptibility to viral hepatitis (OR: 0.89, 95% CI: 0.81-0.98, P = 0.02) and infectious mononucleosis (OR: 0.91, 95% CI: 0.84-0.98, P = 0.02) were associated with a decreased risk of colon cancer, while measles virus (OR: 1.41, 95% CI: 1.07-1.85, P = 0.01) was associated with an increased risk of colon cancer. Presence of SNPs linked to increased susceptibility to herpes zoster (OR: 1.26, 95% CI: 1.05-1.52, P = 0.01) was associated with an increased risk of rectal cancer, while infectious mononucleosis (OR: 0.809, 95% CI: 0.80-0.98, P = 0.02) was associated with a decreased risk.

Conclusion: The study provides the first evidence of the genetic susceptibility associations between different viral infections and CRC, enhancing our understanding of the etiology of CRC.