Overall, HER2 expression profiles are highly concordant between admixed in situ and invasive breast cancer, but overexpression/amplification is less common in the DCIS component of admixed lesions than in pure DCIS (Burkhardt et al., 2010; Lambein et al., 2017; Latta et al., 2002; Park et al., 2006). The gene discussed is ERBB2; the disease is ductal breast carcinoma in situ.