The NorCUP Trial: Improving Prognosis and Personalized Treatment in Cancer of Unknown Primary (CUP)

Inclusion Criteria: * ECOG PS 0-2. * Life expectancy minimum 3 months. * Radiologically verified metastatic disease (CT thorax/abdomen/pelvis) with no radiological signs of primary tumor. * Histologically verified metastatic disease of unknown primary. Morphological and immunohistochemical findings suggesting a possible, but not definitive, origo is eligible. * Eligible histologies include adenocarcinoma, squamous cell carcinoma, poorly and undifferentiated carcinoma and undifferentiated neoplasms. * Clinically relevant endoscopic examinations have been performed as indicated by clinical, radiological and pathological findings, without identification of a primary tumor. * Clinically relevant supplementary radiological examinations have been performed as indicated by clinical, radiological and pathological findings, with no radiological signs of primary tumor (e.g. PET/CT, mammography/MR mammae). * Metastatic lesion available for biopsy. Protocol deviation may be allowed if lesion is not technically available for biopsy. For patients with metastatic lesion technically available for biopsy, the patient must be deemed medically fit to undergo a metastatic biopsy, as assessed by the investigator. * Capable of giving signed informed consent as described in Appendix 1, which includes compliance with the requirements and restrictions listed in the ICF and in this protocol. Exclusion Criteria: * Patients with any clinically significant medical or psychiatric condition which, in the opinion of the treating physician, makes it undesirable for the patient to participate in the study or which could jeopardize compliance with study requirements. * Psychological, familial, sociological or geographical condition(s) potentially hampering compliance with the study protocol and follow-up schedule; those conditions should be discussed with the patient before registration in the trial * Patient not able to give an informed consent or comply with study regulations as deemed by study investigator.