ERBB2 and breast ductal adenocarcinoma: HER2 gene amplification was associated with higher histological grade (45% in non-amplified vs. 66% in amplified, p < 0.001), ductal carcinoma (75% in non-amplified vs. 87% in amplified, p < 0.001), negative receptor status (16% in non-amplified vs. 44% in amplified, p < 0.001) and high Ki67 (64% in non-amplified vs. 79% in amplified, p < 0.001), while TOP2A amplification was associated with higher histological grade (58% in deleted vs. 49% in non-amplified vs. 62% in amplified, p = 0.023) and negative receptor status (37% in deleted vs. 20% in non-amplified vs. 40% in amplified, p < 0.001).