If left ventricular ejection fraction (LVEF) deteriorates during cancer treatment (from >10% to <50%), or myocardial strain decreases (>15% change in GLS), early initiation of cardioprotective therapies (angiotensin-converting enzyme inhibitors, angiotensin or beta receptor blockers) is recommended, and LVEF should be reassessed before discontinuation. The gene discussed is ACE; the disease is cancer.