Carcinoma, Signet Ring CellAdenocarcinomaStomach NeoplasmsAdenocarcinoma, MucinousAppendiceal NeoplasmsUmbilicusGastrectomyImmunohistochemistryCarcinomaMicrosatellite InstabilityNeoplasm StagingMucinsRare DiseasesGastric MucosaPeritoneal NeoplasmsCadherinsPrognosisProto-Oncogene Proteins B-rafEndoscopy, GastrointestinalCarcinoma, Squamous CellNeoplasm InvasivenessColorectal NeoplasmsCardiaPyloric AntrumLoss of Heterozygosityras ProteinsEsophageal NeoplasmsHistocytochemistryCarcinoma, HepatocellularSurvival AnalysisMicrosatellite RepeatsTumor Markers, BiologicalAlcian BlueHelicobacter pyloriMutationHelicobacter Infections