TF and breast cancer: Some randomized controlled studies have reported that TF level is positively related to the incidence of ER-negative BC (Hou et al., 2021); the dietary iron supplementation is negatively correlated with the risk of BC; but in the postmenopausal women, heme iron is positively correlated with the risk of ER-positive and/or PR-positive BC (Chang et al., 2020).