ERBB2 and ductal breast carcinoma in situ: The finding that 9% of invasive cancers progressing from low- and intermediate-grade DCIS were HER2 positive/amplified clearly requires further evaluation, as HER2 positivity in low-grade DCIS is exceptional; as example, 0% of low-grade DCIS was HER2 positive compared to 10% of intermediate-grade and 90% of high-grade disease in 646 cases in one recent study [39].