ESR1 and breast cancer: It was consistent with some studies declaring that breast cancer patients with ER (+) in tumor cells have higher rates of bone metastasis compared to patients with ER (−), while breast cancer patients with ER (−) in tumor cells have higher rates of other organs (such as brain, lung, liver) metastasis compared to patients with ER (+) (31, 32), and this may affect the effectiveness of the proportion of ER in predicting unsuspected metastasis lesions in the whole body (N group AUC=0.704 vs. C group AUC=0.647).