Gastrointestinal NeoplasmsUpper Gastrointestinal TractStomach NeoplasmsGastrointestinal TractEsophageal NeoplasmsPancreatic NeoplasmsDigestive SystemAdenocarcinomaGastrointestinal DiseasesEndoscopy, GastrointestinalGastrointestinal HemorrhageColorectal NeoplasmsFluorouracilDuodenitisEsophageal DiseasesCausticsStomachEndoscopyLiver NeoplasmsGastroscopyDuodenumBurns, ChemicalColonic NeoplasmsDuodenoscopyStomach DiseasesEndoscopes, GastrointestinalPeptic UlcerEsophagoscopyEsophagusTreatment OutcomeGastric MucosaDuodenal NeoplasmsGastrointestinal MotilityEndoscopy, Digestive SystemEsophagitisIleostomyDigestive System Surgical ProceduresStomach UlcerDyspepsiaGastritisIntestinal MucosaDigestive System Physiological PhenomenaGastric JuiceIntestine, SmallIleumNeoplasms, Multiple PrimaryMucous MembraneBarrett EsophagusAdministration, OralGastroesophageal RefluxHelicobacter InfectionsAnti-Inflammatory Agents, Non-SteroidalBiopsyHelicobacter pyloriLower Gastrointestinal TractRetrospective StudiesProspective StudiesTime FactorsPostoperative ComplicationsUpper ExtremityUrinary Tract InfectionsIntestinesHematologic NeoplasmsRisk Factors