ERBB2 and breast cancer: A 72-year-old Jehovah's Witness woman with a past medical history of hypertension, hyperlipidemia, and hormone receptor (HR)-negative/human epidermal growth factor receptor 2 (HER2)-positive, stage IA (pT1cpN1M0) left breast cancer, treated with radical mastectomy, adjuvant docetaxel, carboplatin, trastuzumab (TCH), and adjuvant radiation and having completed maintenance trastuzumab about three years ago, now on active surveillance, initially presented to the emergency department for shortness of breath for the past two weeks.