Esophagogastric JunctionAdenocarcinomaStomach NeoplasmsEsophageal NeoplasmsGastroesophageal RefluxCardiaHernia, HiatalEsophagusBarrett EsophagusEsophagoscopyEsophageal DiseasesManometryEsophageal pH MonitoringMetaplasiaEsophagectomyFundoplicationStomachEsophageal AchalasiaGap JunctionsFluorouracilTreatment OutcomeCisplatinGastrectomyIntercellular JunctionsTight JunctionsAntineoplastic Combined Chemotherapy ProtocolsEsophagitisNeoplasm Staging