Unknown Primary: Statistics

Approved by the Cancer.Net Editorial Board, 08/2021

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 32,880 people (16,270 men and boys and 16,610 women and girls) will be diagnosed this year.

Recent statistics indicate that the incidence of CUP is decreasing. This is in part because while some patients are initially diagnosed with CUP, the diagnosis is changed when a primary site is identified at a later date. However, the decreased incidence of CUP is mostly due to improvements in diagnostic clinical and pathologic testing, which more often identifies the site of origin. As additional new diagnostic tests 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, the 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. Also, the estimate may not show the results of better diagnosis or treatment in recent years. 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 & Figures 2021, and the ACS website (sources accessed February 2021).

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.