ESR1 and metastatic malignant neoplasm in the lymph nodes: Multivariate Cox regression analysis indicated that lymph node metastasis (P = 0.090), estrogen receptor (P = 0.149), progesterone receptor (P = 0.157), and p53 status (P = 0.136) showed a trend for an independent prognostic factor for predicting the overall survival of BRCA1-mutated breast cancer patients (Supplementary Table S1).