MethotrexateStomachStomach NeoplasmsPolyglutamic AcidAntirheumatic AgentsFolic Acid AntagonistsTetrahydrofolate DehydrogenaseStomach DiseasesArthritis, RheumatoidAminopterinAntimetabolites, AntineoplasticLeukemia L1210Reduced Folate Carrier ProteinTrimetrexateGastric MucosaStomach UlcerFolic AcidDrug Therapy, Combinationgamma-Glutamyl HydrolaseLeucovorinTetrahydrofolatesAbortifacient Agents, NonsteroidalCyclophosphamideTreatment OutcomeDrug ResistanceAntineoplastic Combined Chemotherapy ProtocolsImmunosuppressive AgentsDrug Administration ScheduleVincristineSulfasalazineDeoxyuridinePrecursor Cell Lymphoblastic Leukemia-Lymphoma6-MercaptopurineFluorouracilDermatologic AgentsPregnancy, EctopicFormyltetrahydrofolatesDose-Response Relationship, DrugFolate Receptors, GPI-AnchoredDoxorubicinPhosphoribosylaminoimidazolecarboxamide FormyltransferasePyloric AntrumOsteosarcomaInjections, SpinalPrednisoneCytarabineThymidylate SynthaseLeukemia, LymphoidHydroxychloroquineCentral Nervous System NeoplasmsPregnancy, TubalTime FactorsSarcoma 180Pteroylpolyglutamic AcidsIsoxazolesStomach RupturePsoriasisAsparaginaseBiological TransportGastric FundusGestational Trophoblastic DiseaseRemission InductionAdministration, OralHydroxymethyl and Formyl TransferasesProbenecidDigestive SystemStomach VolvulusAntibodies, MonoclonalMucositisDouble-Blind MethodCombined Modality TherapyGastrectomyDuodenumNucleotide DeaminasesCarcinoma, Ehrlich TumorGastric JuiceVinblastineArthritis, JuvenileArthritis, PsoriaticCisplatinTrophoblastic NeoplasmsGastrointestinal MotilityBreast NeoplasmsHelicobacter pyloriGastroscopyKineticsSurvival AnalysisGastric AcidLeukemia L5178LymphomaInfusions, ParenteralAntineoplastic AgentsSeverity of Illness IndexHypoxanthinesNeoplasms