Egg consumption and risk of bladder cancer: a meta-analysis

The findings of epidemiologic studies on the association between egg consumption and bladder cancer risk remain conflicting. We conducted a meta-analysis to clarify the potential association between egg consumption and bladder cancer risk. Four cohort studies and 9 case-control studies in the PubMed database through February 2012 were identified on egg consumption and risk of bladder cancer involving 2715 cases and 184,727 participants. Random-effects models were used to calculate the summary relative risk estimates (SRRE) based on the highest compared with the lowest category of egg consumption. In addition, we performed stratified analyses and sensitivity and dose-response analyses to examine the association. Overall, no significant association was observed between egg consumption and bladder cancer (SRRE = 1.11 95% CI: 0.90-1.35). However, increased risk of bladder cancer was detected in North/South America (SRRE = 1.40 95% CI: 1.05-1.86) and, moreover, fried egg intake positively associated with bladder cancer as well (SRRE = 2.04, 95% CI: 1.41-2.95). In conclusion, our findings suggest no significant association between egg consumption and bladder cancer risk, except for a possible positive relationship with the intake of fried eggs based on the limited number of studies. Additional studies, especially large prospective cohort studies, are warranted to confirm these findings.