About Cancers of Unknown Primary Origin


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Cancer of unknown primary origin (CUP) is a rare disease where cancer cells are found in the body, but the place where the cancer began is unknown. Sometimes the site where the cancer began is never found.

When tests to diagnose cancer show a different type than was expected, doctors may diagnose the disease as CUP. For example, if tissues from the lung show uterine cancer when there is no sign of cancer in the uterus, it is called a CUP.

Signs & Symptoms

These are signs of cancer of unknown primary:

  • Lump or thickening in any part of the body
  • Pain that does not go away in one part of the body
  • Coughing or hoarseness that does not go away
  • Change in bowel or bladder habits
  • Unusual bleeding or discharge
  • Fever that does not go away
  • Night sweats
  • Unexplained weight loss or loss of appetite

Many other health problems can also cause these signs. If you have any of these signs, see your doctor as soon as possible.

Learn more about cancers of unknown primary from the National Cancer Institute.

Image of Cancers of Unknown Origin

In cancers of unknown primary origin, cancer cells have spread in the body but the place where the cancer began is not known.

Specialties & Treatments

Huntsman Cancer Institute provides comprehensive, compassionate, state-of-the-art care for cancers of unknown primary origin. Our experts treat and diagnose all types of cancers and conditions.

Huntsman Cancer Institute offers different types of treatment for people with cancer of unknown primary. These are the most common:

  • Surgery
  • Radiation therapy
  • Chemotherapy
  • Hormone therapy

The treatment or combination of treatments each patient has depends on the stage of the cancer, recommendations of the care team, and the patient's wishes.

Learn more about types of cancer treatments and cancer screenings.

Causes & Risk Factors

Cancers of unknown primary origin are extremely rare. The causes and risk factors for CUPs are unknown.

Diagnosis & Staging

Diagnosis of CUPS

Doctors use these tests to screen for and diagnose cancer of unknown primary cancer:

  • Physical exam and history: A health care provider examines your body for signs of disease. Your personal health habits, past illnesses, and symptoms help guide the exam.
  • Laboratory tests: Through testing body tissues, blood, urine, or other substances in the body, your health care team can check to see how the liver and other organs are functioning. They can also look for substances that cells produce when cancer is present.
  • Fecal occult blood test (FOBT): This test looks for small amounts of blood in the stool. The stool sample is usually collected at home and delivered to the laboratory for testing. Blood in the stool may be a sign of cancer in the colon.
  • Biopsy: The health care provider removes cell or tissue samples so they can be viewed under a microscope to check for signs of cancer.

Staging of CUPS

There is no standard staging system for cancer of unknown primary.

Learn more about staging cancers of unknown primary from the National Cancer Institute.