Survival statistics for cancer of unknown primary

Last medical review:

Survival statistics for cancer are very general estimates and must be interpreted very carefully. Because these statistics are based on the experience of large groups of people, they cannot be used to predict a particular person’s chances of survival.

Cancer of unknown primary (CUP) means that it is hard to find where the cancer first started (called the primary site). When doctors can't find the primary site, it is hard to know which treatments will be the most effective. 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. 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. It may include statistics from other countries that are likely to have similar outcomes as in Canada.

Survival statistics for CUP are often reported as median survival. Median survival is the length of time after diagnosis or the start of treatment at which half of the people with CUP are still alive. In other words, half of the people diagnosed with CUP are expected to live at or beyond the median survival and the other half are not. The median survival in people diagnosed with CUP is 8 to 12 months.

Fewer than 25% of people diagnosed with CUP will be alive 1 year after diagnosis. Fewer than 10% will be alive 5 years after diagnosis.

Questions about survival

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

  • your health history
  • the type of cancer
  • certain aspects of the cancer, such as where it has spread to in the body
  • the treatments chosen
  • how the cancer responds 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

  • Tien Le , MD, FRCSC, DABOG
  • American Cancer Society . Cancer of Unknown Primary Early Detection, Diagnosis, and Staging . 2018 :
  • American Society of Clinical Oncology (ASCO). Unknown Primary: Statistics. 2022:
  • PDQ Adult Treatment Editorial Board. Carcinoma of Unknown Primary Treatment (PDQ®) – Health Professional Version. Bethesda, MD: National Cancer Institute; 2018:
  • National Comprehensive Cancer Network . NCCN Clinical Practice Guidelines in Oncology: Occult Primary (Cancer of Unknown Primary) Version 1.2023 . 2022 .
  • Yentz S, Bhave M, Cobain E, Baker L. Cancer of Unknown Primary. DeVita VT Jr., Lawrence TS, Rosenberg SA, eds. DeVita, Hellman, and Rosenberg's Cancer: Principles & Practice of Oncology. 11th ed. Philadelphia, PA: Wolters Kluwer; 2019: Kindle version, ch 108, .
  • Fizazi K, Greco FA, Pavlidis N, Daugaard G, Oien K, Pentheroudakis G . Cancers of unknown primary site: ESMO clinical practice guidelines for diagnosis, treatment and follow-up . Annals of Oncology . 2015 : 26(Supplement 5):v133–v138 .

Medical disclaimer

The information that the Canadian Cancer Society provides does not replace your relationship with your doctor. The information is for your general use, so be sure to talk to a qualified healthcare professional before making medical decisions or if you have questions about your health.

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