Egg intake and the risk of glioma and head and neck cancers: a systematic review and dose-response meta-analysis of observational studies

Findings on the relationship between egg consumption and risk of glioma and head and neck cancer (HNC) are conflicting. A 2019 meta-analysis reported no significant association between egg intake and glioma risk. However, several eligible articles have been published since the release of that meta-analysis. In addition, there is no evidence of a dose-response relationship in this regard. Also, we found no meta-analysis investigating the association between egg intake and HNC. Therefore, we aimed to conduct a comprehensive meta-analysis to summarize current evidence on the relationship between egg consumption and the risk of glioma and HNC. We systematically searched PubMed, Scopus, Web of Sciences, and Google Scholar until August 2024, for observational studies that reported the association between egg consumption and the risk of glioma and HNC. In total, eleven studies, including seven studies on glioma and four studies on HNC, were included in the current meta-analysis. These studies included 1,274,437 participants with 4199 cases of glioma and 3164 cases of HNC. The meta-analysis was performed using a random-effects model. We found that egg consumption was associated with a reduced risk of glioma, particularly in Eastern populations (i.e. Asian populations) (RR: 0.51, 95% CI: 0.35-0.73). Additionally, in the non-linear dose-response analysis, egg consumption above 50 grams per day (>1 egg/day) gradually increased the risk of HNC. In conclusion, we found a significant inverse association between egg and glioma risk among Eastern populations and a positive association between egg intake and HNC risk in the dosages of >50 grams per day.