Patients will be evaluated by a Dynamic PET-CT protocol: before initiation of therapy, 7-14 days after the first therapy cycle, 3 months after initiation of therapy and 6 months after the first therapy cycle. In addition, non-invasive biomarkers that are routinely measured including protein markers (CEA- Carcinoembryonic Antigen, CYFRA21- Cytokeratin 19 Fragment, NSE- Neuron Specific Enolase) will be assessed in this trial.