Cancer PainVisceral PainGastrointestinal NeoplasmsCancer of Gastrointestinal TractSmall Intestine CancerPancreas CancerLiver CancerColon CancerBiliary Tract CancerStomach CancerRectum CancerPeritoneal CancerGastrointestinal Cancer MetastaticGastrointestinal Cancers - AnusGastrointestinal Cancers - StomachGastrointestinal Cancers - ColorectalGastrointestinal Cancers - Small IntestineSmall Intestine Cancer Stage IIISmall Intestine Cancer Stage IVSmall Intestine Cancer, RecurrentPancreas Cancer, Stage IIIPancreas Cancer, Stage IVPancreas Cancer, MetastaticPancreas Cancer, RecurrentLiver Cancer Stage IIIaLiver Cancer Stage IIIbLiver Cancer Stage IIIcLiver Cancer Stage IVColon Cancer Stage IIIColon Cancer Stage IVStomach Cancer Stage IIIStomach Cancer Stage IVStomach Cancer RecurrentRectum Cancer, RecurrentGastrointestinal Cancers - LiverAnal CancerAnal Cancer Stage IIIAnal Cancer Stage IVAnal Cancer RecurrentAnal Cancer MetastaticAnal Cancer, Stage IIIAAnal Cancer, Stage IIIBAppendix CancerAmpullary CancerBile Duct CancerBile Duct Cancer Stage IIIBile Duct Cancer Stage IVBile Duct Cancer Stage IVABile Duct Cancer Stage IVBBile Duct Cancer RecurrentCarcinoid TumorCarcinoid Tumor of PancreasCarcinoid Tumor of Large IntestineCarcinoid Tumor of GI SystemCarcinoid Tumor of ColonCarcinoid Tumor of LiverCarcinoid Tumor of CecumCarcinoid Tumor of IleumCarcinoid Tumor of RectumCarcinoid Tumor of the Small BowelCarcinoid Tumor of the StomachLarge Intestine CancerEsophagus CancerEsophagus Cancer, Stage IIIEsophagus Cancer, Stage IVEsophagus Cancer, RecurrentGallbladder CancerGallbladder Cancer Stage IIIGallbladder Cancer Stage IVGastric (Stomach) CancerNeuroendocrine TumorPeritoneum CancerRectal CancerEsophagus Cancer, Stage IEsophagus Cancer, Stage IIGallbladder Cancer Stage IGallbladder Cancer Stage IIBile Duct Cancer Stage IBile Duct Cancer Stage II