The incidence of gastric cancer is decreasing worldwide, but the prognosis is still generally poor. Insight in pathogenesis (the role of Helicobacter Pylori and Epstein‐Barr virus) and molecular genetics (p53 en RAS mutations) has increased in recent years. Important new data exist on treatment: the role of local surgical treatment, extended lymphadenectomy, and chemotherapy. Outcome is clearly dependent on many factors, but complete surgical excision is still central in the treatment. This chapter deals with clinical, pathological, and genetic factors that are related to survival, especially those that can influence clinical management. An important caveat has been formulated recently: criteria to diagnose cancer of the stomach vary, clearly leading to differences in patient populations in studies. In particular, this might partially explain the higher incidence and better prognosis of gastric cancer in Japan. But then, when staged similarly using the same prognostic factors, there was no difference between the prognosis for German and Japanese patients. Where prior gastric surgery is concerned (gastric stump carcinoma) prognosis is very poor, but dependant on stage. Histology and DNA index in these cases are the same as for other upper‐third stomach cancer cases. In a retrospective study on 2654 patients from Japan, it was found that from the early 1960s to the early 1980s the percentage of proximally located tumors increased from 17% to 27% and signet‐ring‐cell carcinoma increased from 2% to 22%. Although proximally located tumors behaved more aggressive, survival was more associated with stage than with primary site in the stomach.