In January 2010, the European Medicines Agency (EMA) extended the indication for the use of trastuzumab (Herceptin®), a humanised monoclonal antibody that binds to the human epidermal growth factor 2 (HER2) protein, for the first line treatment of patients with HER2 positive metastatic adenocarcinoma of the stomach or gastroesophageal junction. The decision was based on one phase III study, which showed improved overall survival of patients treated with trastuzumab in combination with standard chemotherapy (5-FU or capecitabine plus cisplatin) compared to patients treated with standard chemotherapy alone. Despite limitations of the available data, it is reasonable to offer trastuzumab in addition to standard chemotherapy to patients with tumours expressing high levels of HER2 protein, as long as they do not have a contraindication to trastuzumab.