In a small number of cancer patients, a secondary tumor is diagnosed, but no primary cancer can be found, in spite of extensive tests. When cancer has metastasized, it may be treated with chemotherapy , radiation therapy , biological therapy , hormone therapy , surgery , or a combination of these. The choice of treatment generally depends on the type of primary cancer, the size and location of the metastasis, the patient's age and general health, and the types of treatments used previously. In patients diagnosed with CUP, it is still possible to treat the disease even when the primary tumor cannot be located. New cancer treatments are currently under study.
Clinical trials are a critical step in the improvement of treatment.
Before any new treatment can be recommended for general use, doctors conduct studies to find out whether the treatment is both safe for patients and effective against the disease. The results of such studies have led to progress not only in the treatment of cancer, but in the detection, diagnosis , and prevention of the disease as well. Patients interested in participating in research should ask their doctor to find out whether they are eligible for a clinical trial.