A phase III study using trastuzumab, a humanized monoclonal antibody against HER2, in combination with chemotherapy showed a survival benefit in patients with advanced gastric / esophagogastric junction cancer in patients with amplification and / or overexpression of HER2, reducing the risk of death by 26% compared with chemotherapy alone, increasing median overall survival from 11.1months to 13.8 months (p = 0.0046).