Although, about 90% of stomach tumors are adenocarcinomas [7], several factors lead to biologically and clinically GC subsets: antecedent tumorigenic conditions, such as Helicobacter pylori gastritis and other chronic gastric pathologies; location of the primary tumor (cardia and noncardia region); subtypes of adenocarcinoma (diffuse, intestinal, or mixed [16]); ethnicity of the afflicted population (differing levels of susceptibility and aggressiveness of the tumors); and a predictive biomarker (ERBB2) [15]. The gene discussed is ERBB2; the disease is adenocarcinoma.