Family members of CUP patients at higher risk of developing CUP themselves
 

Cancer usually begins in one location and then spreads, but in 3 percent to 5 percent of cancer patients, the tissue where a cancer begins is unknown. In these individuals a cancer diagnosis is made because it has metastasized to other sites. Patients with these so-called "cancers of unknown primary," or CUP, have a very poor prognosis, with a median survival of three months.

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