Most patients appear to have a carcinoma of unknown primary site. Other tumors may be difficult to classify. Some cancer forms are sensitive to chemotherapy, but multiple studies have concluded that chemotherapy does not increase survival for patients with CUP. The realistic benefit of treatment is usually symptom-relief and improvement in quality of life, but only a moderate improvement in survival in patients with good prognostic signs.
ESMO (European Society for Medical Oncology) has created a treatment recommendation for the unknown primary site diagnosis based on histology and extent (6,7).