A dose-response meta-analysis of coffee consumption and thyroid cancer occurrence

The relationship between coffee consumption and thyroid cancer (TC) occurrence has been evaluated in several observational studies with controversial results. The study aims to examine the associations between coffee consumption and TC occurrence. Systematic searches up to February 2019 were conducted. We estimated summary adjusted relative risks (RRs) and the corresponding 95% confidence intervals (CIs). The dose-response analysis was conducted by using generalised least square trend estimation. A total of ten studies involving 379,825 participants and 1,254 TC cases were included. The total summary RR showed that high coffee consumption was a protection factor of TC (RR = 0.75; 95% CI, 0.62-0.91). With the linear cubic spline model, the occurrence of TC was reduced by 5% with each one cup/day increment of coffee consumption (RR = 0.95; 95% CI, 0.91-0.99).This meta-analysis provides quantitative evidence that coffee consumption was inversely associated with the TC occurrence in a linear dose-response manner.