ESR1 and breast cancer: Data mining from The Cancer Genome Atlas (TCGA) dataset for breast cancer showed significant overexpression of CDCA2 in some subtypes of breast cancer, which were Erb-B2 Receptor Tyrosine Kinase 2/Estrogen receptor/progesterone receptor (ERBB2/ER/PR) negative (triple-negative breast cancer [TNBC]), invasive ductal breast carcinoma, invasive breast carcinoma, and invasive lobular breast carcinoma.