SLCO1B3 and metastatic malignant neoplasm in the lymph nodes: In addition, lymph node metastasis (HR = 7.346, P < 0.001), vascular invasion (HR = 4.545, P = 0.043), histological grade (HR = 3.762, P = 0.003), PR status (HR = 0.267, P = 0.002) and SLCO1B3 expression (HR = 0.275, P = 0.002) were independently associated with the OS of ER + breast cancer patients (Table 5).