Multivariate analysis revealed that post‐2017 treatment (HR 0.79, 95% CI 0.66–0.96; p = 0.02) and HER2‐positive status (HR 0.75, 95% CI 0.58–0.97; p = 0.03) were significantly favorable prognostic factors while diffuse type (HR 1.53, 95% CI 1.19–1.96; p < 0.01), an ECOG of PS 2 (HR 2.52, 95% CI 1.71–3.70; p < 0.01), lymph node metastasis (HR 1.39, 95% CI 1.09–1.76; p < 0.01), liver metastasis (HR 1.59, 95% CI 1.28–1.98; p < 0.01), and peritoneal metastasis (HR 1.94, 95% CI 1.56–2.40; p < 0.01) were significantly poor prognostic factors (Table 2). Here, ERBB2 is linked to metastatic malignant neoplasm in the lymph nodes.