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- Cancer Information
For medical questions, we encourage you to review our information with your doctor.
- Can a Cancer of Unknown Primary Be Found Early?
- Signs and Symptoms of a Cancer of Unknown Primary
- Tests for a Cancer of Unknown Primary
- Testing for a Cancer of Unknown Primary by Location
- Cancer of Unknown Primary Stages
- Survival Rates for a Cancer of Unknown Primary
- Questions to Ask About a Cancer of Unknown Primary
- Surgery for a Cancer of Unknown Primary
- Radiation Therapy for a Cancer of Unknown Primary
- Chemotherapy for a Cancer of Unknown Primary
- Hormone Therapy for a Cancer of Unknown Primary
- Targeted Therapy for a Cancer of Unknown Primary
- Other Drugs for a Cancer of Unknown Primary
- Treatment of a Cancer of Unknown Primary by Location
- Palliative Care for a Cancer of Unknown Primary
- If You Have Cancer of Unknown Primary
Key Statistics for Cancers of Unknown Primary
How common are cancers of unknown primary?
The exact number of cancers of unknown primary (CUP) diagnosed each year is unknown, because some cancers start out being diagnosed as unknown primary, but the primary site is found later. Still, the American Cancer Society estimates that about 34,950 cases of cancer of unknown primary will be diagnosed in 2024 in the United States. This number represents about 2% of all cancers. As more sophisticated lab tests become available to determine where a cancer started, the number of cancers of unknown primary may go down.
Visit the American Cancer Society’s Cancer Statistics Center for more key statistics.
The American Cancer Society medical and editorial content team
Our team is made up of doctors and oncology certified nurses with deep knowledge of cancer care as well as editors and translators with extensive experience in medical writing.
American Cancer Society. Facts & Figures 2024. American Cancer Society. Atlanta. 2024.
Bochtler T, Löffler H, Krämer A. Diagnosis and management of metastatic neoplasms with unknown primary. Semin Diagn Pathol. 2018 May;35(3):199-206. doi: 10.1053/j.semdp.2017.11.013. Epub 2017 Nov 26. PMID: 29203116.
Howlader N, Noone AM, Krapcho M, et al (eds). SEER Cancer Statistics Review, 1975-2014, National Cancer Institute. Bethesda, MD, https://seer.cancer.gov/csr/1975_2014/, based on November 2016 SEER data submission, posted to the SEER website, April 2017.
Mnatsakanyan E, Tung WC, Caine B, Smith-Gagen J. Cancer of unknown primary: Time trends in incidence, United States. Cancer Causes Control. 2014 Jun;25(6):747-57. doi: 10.1007/s10552-014-0378-2. Epub 2014 Apr 8.
Varadhachary GR, Lenzi R, Raber MN, Abbruzzese JL. Carcinoma of Unknown Primary In: Neiderhuber JE, Armitage JO, Doroshow JH, Kastan MB, Tepper JE, eds. Abeloff’sClinical Oncology. 5th ed. Philadelphia, PA. Elsevier: 2014:1792-1803.
Last Revised: May 27, 2024
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