Liu et al. [68] proved that the protein expression levels of IDH1 were gradually decreased during breast cancer progression: from the normal tissue, through ductal carcinoma in situ (DCIS), to invasive cancer; whereas Minemura et al. [69] reported that a high IDH2 status was found to be significantly linked to poorer patient prognosis and was identified as an independent prognostic factor for patients with estrogen-receptor positive status. Here, ESR1 is linked to breast cancer.