Prognostic Significance of HER2 Expression for Gastric Cancer with Clinically Para-aortic Lymph Node Metastasis after Chemotherapy

Objective: The prognosis of gastric cancer with para-aortic lymph node (PAN) metastasis is extremely poor. Trastuzumab-based chemotherapy is recommended in patients with HER2-positive expression. However, the clinical significance of HER2 expression remains unclear in patients with PAN metastasis after chemotherapy. Methods: We retrospectively enrolled a total of 41 patients with clinically PAN metastasis from gastric cancer who underwent chemotherapy. HER2 expression was assessed before chemotherapy. Results: 18 patients had HER2-positive tumors and the frequency of HER2-positive status was 43.9% (18/41). According to tumor response, 1 and 17 patients had complete response and partial response, respectively. Eleven patients underwent gastrectomy after chemotherapy. HER2 status was significantly correlated with the number of distant metastatic sites (1 vs. ≧2), the presence or absence of trastuzumab-based chemotherapy, and the presence or absence of gastrectomy (p=0.0192, p＜0.0001, and p=0.0046, respectively). Patients with HER2-positive status had a significant better prognosis than those with HER2-negative status (p=0.0003). Multivariate analysis related with pre-therapeutic factors showed age (＜70 vs. ≧70 years) and HER2 status as an independent prognostic factor (p=0.0153 and p=0.0385, respectively). Conclusion: Our study demonstrated that the assessment of HER2 expression has the clinical utility for predicting prognosis in patients with PAN metastasis from gastric cancer.