Gastrointestinal Stromal TumorsProto-Oncogene Proteins c-kitGastrointestinal NeoplasmsBenzamidesPiperazinesPyrimidinesReceptor, Platelet-Derived Growth Factor alphaStromal CellsAntineoplastic AgentsMesenchymomaNeoplasms, Connective TissueMitotic IndexEpithelioid CellsPyrrolesDuodenal NeoplasmsImmunohistochemistryLeiomyosarcomaTumor Markers, BiologicalIleal NeoplasmsNeoplasms, Multiple PrimaryJejunal NeoplasmsMutationIntestinal NeoplasmsSex Cord-Gonadal Stromal TumorsIndolesStomach NeoplasmsTomography, X-Ray ComputedProtein Kinase InhibitorsDigestive System Surgical ProceduresDNA Mutational AnalysisNeurofibromatosis 1Tumor BurdenSarcomaTreatment OutcomePrognosisCell Line, TumorCarney ComplexGastrectomyAntigens, CD34LeiomyomaDrug Resistance, NeoplasmDisease-Free SurvivalInterstitial Cells of CajalExonsEndosonographyLaparotomyNeurilemmomaRetrospective StudiesSomatostatinomaS100 ProteinsProtein-Tyrosine KinasesNeoplasm MetastasisDisease ProgressionLeiomyoma, EpithelioidPositron-Emission TomographyTumor Necrosis Factor-alphaCell ProliferationGastroscopyPeritoneal NeoplasmsDNA, NeoplasmLiver NeoplasmsKi-67 AntigenSoft Tissue NeoplasmsNeoplasm ProteinsEndoscopy, GastrointestinalElectron Transport Complex IIGene Expression Regulation, NeoplasticIncidental FindingsDouble-Balloon EnteroscopyOmentumNeurofibrosarcomaPelvic NeoplasmsNeoplasm StagingNeoplasm Recurrence, LocalNeoadjuvant TherapyBiopsy, NeedleSuccinate DehydrogenaseSurvival RateGastrointestinal HemorrhageIntestine, SmallHemoperitoneumAdenocarcinomaFollow-Up StudiesLethargySurvival AnalysisKaplan-Meier EstimateSignal TransductionMeckel DiverticulumEndometrial Stromal TumorsWilms TumorFluorodeoxyglucose F18Cecal NeoplasmsCombined Modality TherapyXenograft Model Antitumor AssaysCarcinoid TumorReverse Transcriptase Polymerase Chain ReactionRetroperitoneal NeoplasmsGene Expression ProfilingRadiography, AbdominalAmpulla of Vater