Cancer of an Unknown Primary – Information & Support

Unknown Primary Cancer (UPC) or Cancer of Unknown Primary (CUP), or Occult Primary Malignancy (OPM), are terms meaning the same thing:

  • A cancer that has been found in tests, but it’s not clear where it started.
  • Cancer that has spread from somewhere else in the body and the area where its the primary site (Origin) can’t be located in the body.
  • In UPC, symptoms appearing usually are caused by the secondary cancer of which there is normally more than one type of cancer. UPC is when the primary cancer may not be found, even after tests.
  • Once the primary has been found the cancer is no longer a UPC and is renamed.
  • Doctors, from tests, may have some good clues as to where the cancer might have started and this will affect their decision on treatment.
  • It’s important to remember that UPC is different in every person.

Since the exact organ of origin of CUP is not known, it is difficult to identify the risk factors. Smoking may be an important risk factor as more than half of unknown primary cancer patients have a history of smoking.

Other risk factors include:

  • older age
  • diet
  • alcohol
  • obesity

The symptoms of UPC are individual to everyone; no two cases will be identical as it depends on the primary cancer. The following general symptoms are common:

  • weight loss
  • no appetite
  • feeling extremely tired

With UPC, there may be the combination of one or more secondary cancers producing symptoms, which may show up in different and confusing combinations.

Diagnosis occurs when a patient presents with a tumour. Tests may include:

  • physical examination

After visiting a GP a referral will probably be made to a hospital for some tests. As the main goal of tests with UPC, is to find the primary site of the cancer, there may be more tests than usual. These may include:

  • X-rays
  • Blood test: Used in UPC to examine different aspects that may give a clue to the primary site. May show liver, kidney and lung function, internal bleeding, suggesting a bowel or stomach cancer, may show levels of different cells in the blood leading to bone marrow examination and may also show hormone levels, leading to reproductive organ cancers.
  • PET scan
  • Urine tests (urine cytology)
  • FOB (faecal occult blood): A small sample of the patients stool (faeces)
  • PSA (prostate specific antigen)
  • Endoscope: Used to examine organs like the lungs or stomach/bowel
  • Barium x-rays: Used for looking at the digestive system as it doesn’t show up well on ordinary x-rays.

If the results of the test show a UPC, another referral will be made to a multi-disciplinary team (MDT) of doctors and therapists, who specialise in the treatment of different organs and areas of the body.

Although UPC is hard to treat, treatment may help to control it for a time and improve symptoms. Even if the primary hasn’t been found, the specialist may still have a good idea of where the cancer started.

Join CanTeen’s online community to chat with other young people about cancers of an unknown primary, their treatment… or anything really.