ERBB2 and gastric adenocarcinoma: When limiting analysis to only patients with HER2 positivity by IHC (HR = 2.694, 95% CI: 1.146–6.336, P = 0.018) or NGS (HR = 3.641, 95% CI: 1.442–9.194, P = 0.004), patients with HER2+/CCNE1-amplified gastric adenocarcinoma demonstrated significantly worse survival after trastuzumab compared with patients with HER2+/non–CCNE1-amplified gastric adenocarcinoma (Fig. 4D and E).