However, in this study, the PMR of the CDO1 promoter region in serum showed high diagnostic efficiency for BC stages I–IV with a sensitivity of 61.2%, a specificity of 89.7% and an AUC of .75 (95% CI: .68–.83) in cohort II of 113 BC patients, and it was significantly correlated with advanced T stage, advanced N stage, metastasis, TNM stage, HER2 status and molecular phenotypes (p < .05). Here, CDO1 is linked to breast cancer.