ERBB2 and metastatic malignant neoplasm in the lymph nodes: But, ≥ second-line Fulvestrant usage, HER2-positive, higher nuclear or histological grade, late stage (stage III/IV) at BC diagnosis, and lymph node metastases were important risk factors for poor PFS prognosis for Fulvestrant users (Table 2 and Additional file 1: Table S1).