The aim of the study was to compare the efficacy and toxicity of the first-line palliative three-drug chemotherapy with EOX and mDCF regimens, respectively, in patients with (HER2) human epidermal growth factor receptor 2 negative, locally advanced inoperable or metastatic gastric or gastroesophageal junction adenocarcinoma. This evidence concerns the gene ERBB2 and gastroesophageal junction adenocarcinoma.