DCIS: Ductal Carcinoma In Situ, IDC: Invasive Ductal Carcinoma, ILC: Invasive Lobular Carcinoma, ER: Estrogen Receptor, PR: Progesterone Receptor, HER2: Human Epidermal Growth Factor Receptor 2, BMI: Body Mass Index, ECOG: Eastern Cooperative Oncology Group. The gene discussed is ESR1; the disease is breast ductal adenocarcinoma.