Conflicting findings have been the reason that the prognosis of HER2-low BC remains a subject of debate, but the majority agrees that even though the clinicopathological characteristics between HER2-low and HER2-zero were similar between HR-positive and HR-negative BC, the better prognosis of HER2-low tumors has only been consistent in HR-positive patients. The gene discussed is ERBB2; the disease is breast cancer.