ESR1 and metastatic malignant neoplasm in the lymph nodes: Classic clinicopathological features, including tumor size, histological subtypes and grades, lymphatic invasion, lymph node metastasis, estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2) have effective value in guiding clinical decisions; Serum tumor markers, such as carcinoembryonic antigen (CEA), cancer antigen 19-9 (CA19-9), cancer antigen 125 (CA125), cancer antigen 15-3 (CA15-3), have been typically used for follow-up monitoring [3, 4].