GCG and neoplasm: Tests of biochemical markers detecting liver metastases, and for the post treatment follow-up of liver metastases:1) Chromogranin A2) Chromogranin B3) Serotonin4) Tumor specific hormones(Glucose, Insulin, Proinsulin, C-Peptide, Gastrin, Glucagon, Vasoactive Intestinal Peptide, Somatostatin, Neuron Specific Enolase)