A multicenter phase III ToGA trial demonstrated significantly improved survival in HER2+ advanced G/GEJ adenocarcinoma patients who received traditional chemotherapy plus trastuzumab compared to patients who were treated with chemotherapy alone (median OS 13.8 vs. 11.1 months, HR 0.74, 95% CI 0.60–0.91; p = 0.0046) [19]. Here, ERBB2 is linked to gastroesophageal junction adenocarcinoma.