Neoplasms, Unknown PrimaryIncidenceCarcinomaAdenocarcinomaNeoplasmsParaneoplastic Endocrine SyndromesMediastinal NeoplasmsSkin NeoplasmsFluorodeoxyglucose F18Lymphatic MetastasisFatal OutcomeMediastinumAntineoplastic Combined Chemotherapy ProtocolsPositron-Emission TomographyRetrospective StudiesLiver NeoplasmsCarboplatinCisplatinTomography, X-Ray ComputedRadiopharmaceuticalsNeckTreatment OutcomeMelanomaPrognosisLeukopeniaTumor Markers, BiologicalImmunohistochemistryPancreatic NeoplasmsGastrointestinal NeoplasmsLung NeoplasmsNeuroendocrine TumorsDeoxycytidineNeoplasm MetastasisSpinal NeoplasmsBiopsyDrug Administration ScheduleEtoposidePaclitaxelSurvival RateSurvival AnalysisCarcinoma, Squamous CellHead and Neck NeoplasmsMultimodal ImagingProspective StudiesNeoplasms, Cystic, Mucinous, and SerousNeoplasm StagingTomography, Emission-Computed