The most important factor affecting the prognosis of gastric cancer is the extent of the disease at the time of diagnosis. Surgical excision of the tumor is a prerequisite for curative treatment. The patient's prognosis may improve, if cytotoxic therapy is started already before surgical treatment and continued after the treatment. This so-called perioperative cytotoxic therapy also reduces tumor mass. Concomitant chemoradiotherapy has resulted in a prolonged disease-free life span and total life span. It is worthwhile to treat even a disseminated gastric cancer with cytotoxic drugs, and the first targeted therapy is already available.