Unknown Primary: Statistics

Approved by the Cancer.Net Editorial Board, 01/2019

ON THIS PAGE: You will find information about the number of people who are diagnosed with CUP each year. You will also read general information on surviving the disease. Remember, survival rates depend on several factors. Use the menu to see other pages.

CUP is estimated to account for around 2% of all cancer diagnoses in the United States. This means about 31,480 (16,750 men and boys and 14,730 women and girls) patients will be diagnosed this year. The exact number of people diagnosed with CUP each year is not known because some cancers start out being classified as CUP, only to have the primary cancer found later. In other cases, the treating physician makes an educated guess as to the site of origin, based on clinical features and x-ray results, and treats the patient for the presumed diagnosis. As new tests that can more accurately determine where a cancer started become available, the number of people diagnosed with CUP will continue to decrease.

People diagnosed with CUP are a diverse group, and prognosis, which is the chance of recovery, varies widely. When all CUP types are looked at together, average survival time is about 9 to 12 months after diagnosis. However, survival rates vary greatly depending on the where the cancer is located, how much it has spread, cancer cell type, treatments, and more.

Often, treatment options are limited for people with CUP, since the cancer has often spread to several parts of the body before it is diagnosed. However, some patients with CUP have a cancer that can be successfully treated. These differences and survival rates are discussed in the Types of Treatment section of this guide.

It is important to remember that statistics on the survival rates for people with CUP are an estimate. The estimate comes from annual data based on the number of people with this cancer in the United States. Talk with your doctor if you have any questions about this information. Learn more about understanding statistics.

Statistics adapted from the American Cancer Society’s publication, Cancer Facts and Figures 2019, and the ACS website (January 2019).

The next section in this guide is Risk Factors. It explains what factors may increase the chance of developing CUP. Use the menu to choose a different section to read in this guide.