The exact number of people diagnosed with CUP each year is unknown because some cancers start out being classified as unknown primary, only to have the primary found later. However, an estimated 31,860 people will be diagnosed with CUP this year in the United States, which accounts for approximately 2% of all cancers diagnosed. People with CUP are a diverse group, and prognosis (chance of recovery) varies widely. Often, there are not many treatments available for people whose cancer is widespread when diagnosed. However, others have a cancer that can be successfully treated. These differences and survival rates are discussed in the Treatment  section.
Cancer survival statistics should be interpreted with caution. Estimates are based on data from thousands of people with this type of cancer in the United States each year, but the actual risk for a particular individual may differ. It is not possible to tell a person how long he or she will live with CUP. Learn more about understanding statistics .
Statistics adapted from the American Cancer Society.