ERBB2 and breast carcinoma: Importantly, this amplification is subtype specific; 25% of Her2 + breast cancers have a co-amplification of the 17q21.33 region along with the HER2 amplicon while only 6% of Luminal A, 7% of Luminal B, and 1.2% of Basal breast cancers have amplification (Fig. 5b).