Fig. 4

Forest plot of associations between serum/plasma indicators of body iron status (highest vs. lowest category) and breast cancer risk. The diamonds represent the pooled relative risks and corresponding 95% confidence intervals obtained from random-effects meta-analyses. The dots and horizontal lines represent the relative risks and corresponding 95% confidence intervals of individual studies, and the sizes of shaded squares are proportional to the weight contributed by each study to the pooled estimate. I² is the proportion of the total variability attributable to between-study heterogeneity, and P is from Cochran’s Q test evaluating the presence of heterogeneity. *Stevens et al. 2011 [71] reported separate estimates for premenopausal (pre/post) and postmenopausal (post/post) ferritin levels in relation to postmenopausal breast cancer risk; Gaur et al. 2013 [72] reported separate estimates for premenopausal (pre) and postmenopausal (post) breast cancer