HR and invasive ductal breast carcinoma: The ICE3 trial is an Institutional Review Board-approved, prospective, multicentered, non-randomized trial including women ≥ 60 years of age with unifocal, ultrasound visible, invasive ductal carcinoma ≤ 1.5 cm in size, histologic grade 1–2, hormone receptor (HR)-positive, and human epidermal growth factor receptor 2 (HER2)-negative.