Survival statistics for cancer of unknown primary

Cancer of unknown primary (CUP) means that the cancer has already spread, or metastasized, to other parts of the body when it is found. When doctors can’t find the primary cancer, it is hard for them to know which treatments will be the most effective. Both of these factors affect survival.

There are many different ways to measure and report cancer survival statistics. But CUP includes many different types of cancer, which makes it hard to get accurate survival statistics.

Survival statistics for CUP are very general estimates and must be interpreted very carefully. Because these statistics are based on the experience of groups of people, they cannot be used to predict a particular person’s chances of survival. In general, people who are diagnosed with CUP have a poor prognosis. Your doctor can explain the statistics for CUP and what they mean to you.

There are no specific Canadian statistics available for CUP. The following information comes from a variety of sources and may include statistics from other countries.

Survival statistics for CUP are often reported as median survival. Median survival is the period of time (usually months or years) at which half the people diagnosed with CUP are still alive. The other half will live less than this amount of time.

  • Median survival in people diagnosed with CUP is 6 to 10 months.
  • People with a good performance status and a normal lactate dehydrogenase (LDH) level have a median survival of 1 year.
  • Less than 25% of people diagnosed with CUP will be alive 1 year after diagnosis. Less than 10% will be alive 5 years after diagnosis.
  • The median survival in patients with favourable-risk CUP can be much better and the numbers above often do not apply.

Questions about survival

Talk to your doctor about prognosis. Prognosis depends on many factors, including:

  • your medical history
  • type and characteristic of cancer
  • stage
  • treatments chosen
  • response to treatment

Only a doctor familiar with these factors can put all of this information together with survival statistics to arrive at a prognosis.

Expert review and references

  • American Cancer Society. Cancer - Unknown Primary. Atlanta, GA: 2014:
  • Fizazi K, Greco FA, Pavlidis N, et al . Cancers of unknown primary site: ESMO Clinical Practice Guidelines for diagnosis, treatment and follow-up. Annals of Oncology. Oxford University Press; 2011.
  • Greco FA & Hainsworth JD . Cancer of unknown primary site. DeVita VT Jr, Lawrence TS, & Rosenberg SA. Cancer: Principles & Practice of Oncology. 10th ed. Philadelphia: Wolters Kluwer Health/Lippincott Williams & Wilkins; 2015: 113:1720-1737.
  • Cancer Survival Statistics 1992 to 2003 .