Inclusion Criteria:  Diagnosis of a rare subtype of GI cancer including BRAF V600E mutation, MSI-H, HER2 and others Diagnosis of cancer of the gastrointestinal tract may be made by histo- or cyto-pathology, or by clinical and imaging criteria Planned for targeted treatment Age 18 years or older Able to understand written information Consent to samples for translational research  Exclusion Criteria:  Conditions precluding translational blood sampling Another concomitant cancer