DCIS is not one condition but, rather, a spectrum of disease, ranging from indolent lesions more akin to markers of increased risk for hormone-receptor-positive invasive breast cancer with minimal associated mortality to true precursors of triple-negative or HER2 positive invasive cancers that are likely to arise in a one-year to a two-year timeframe with significant associated metastatic potential. The gene discussed is ERBB2; the disease is ductal breast carcinoma in situ.