ESR1 and neoplasm: The focus was on 15 clinical features namely; the number of positive lymph node, Nottingham prognostic index (NPI), cellularity, chemotherapy, estrogen receptor (ER) status measured by immunohistochemistry, human epidermal growth factor receptor 2 (HER2) status, HER2 status measured by single nucleotide polymorphism 6 (SNP6), ER status, integrative cluster, inferred menopausal state, histologic grade, hormone therapy, histological subtype, location of the tumor, and the 3-Gene classifier subtype.