Delaying age at first sexual intercourse provides protection against oral cavity cancer: a mendelian randomization study.

Aim: To investigate whether age at first sexual intercourse could lead to any changes in the risk of oral cavity cancer.

Methods: A two-sample mendelian randomization was conducted using genetic variants associated with age at first sexual intercourse in UK biobank as instrumental variables. Summary data of Northern American from a previous genome-wide association study aimed at oral cavity cancer was served as outcome. Three analytical methods: inverse variance-weighted, mendelian randomization Egger, and weighted median were used to perform the analysis, among which inverse variance-weighted was set as the primary method. Robustness of the results was assessed through Cochran Q test, mendelian randomization Egger intercept tests, MR PRESSO, leave one out analysis and funnel plot.

Results: The primary analysis provided substantial evidence of a positive causal relationship age at first sexual intercourse and the risk of oral cavity cancer (p = 0.0002), while a delayed age at first sexual intercourse would lead to a decreased risk of suffering oral cavity cancer (β = -1.013). The secondary outcomes confirmed the results (all β < 0) and all assessments supported the robustness, too (all > 0.05).

Conclusion: The study demonstrates that a delayed sexual debut would provide protection against OCC, thus education on delaying sexual intercourse should be recommended.