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  • How is cancer of unknown primary diagnosed?

    Contents

    Diagnosis

    Before CUP is diagnosed, you will usually see your GP, who will examine you, send you for tests and refer you to a specialist doctor. The specialist will ask you about your general health and any previous medical problems.

    Initially, the purpose of the tests is to work out whether you have cancer, and whether it is primary or secondary. If the tests show that the cancer is secondary, you will have further tests to try to find the primary cancer.

    The recommended tests for CUP vary depending on your general health, the location of the secondary cancer and the presumed location of the primary cancer. Often several different tests are needed to look for the primary cancer. 

    Blood and urine tests

    A complete blood count checks the levels of red blood cells, white blood cells and platelets. Urine may also be tested for any abnormal cells or substances and to see if there are any problems with organs such as the kidneys or bladder.

    Tumour markers are chemicals made by some cancer cells. Some are found in the blood, but others are found in urine or other body fluids. Your symptoms and gender help the doctor decide if it would be helpful to check for any of these markers. Tumour markers include:

    • prostate specific antigen (PSA)high PSA levels may indicate prostate cancer
    • alpha-fetoprotein (AFP)high AFP levels may be a sign of testicular or liver cancer
    • human chorionic gonadotropin (HCG)high levels of HCG can suggest testicular cancer or a rare type of ovarian cancer
    • carcinoembryonic antigen (CEA)CEA levels may be raised in people who have bowel cancer. Other cancers that may have high CEA levels include lung, pancreatic, stomach, ovarian, breast, thyroid and liver cancers
    • cancer antigen 125 (CA125)CA125 levels may be raised in women with ovarian cancer.

    Biopsy

    A biopsy is the removal of a tissue sample for examination in a laboratory. It is usually the most important test in the diagnosis of CUP because it can show what type of cell has changed, and this indicates where in the body the cancer may have started.

    The tissue sample is often removed under local anaesthetic, but it may sometimes be removed under general anaesthetic. You may have one of the following types of procedures:

    • fine needle aspirationremoves cells using a thin needle
    • core biopsyremoves tissue using a wide needle
    • incisional biopsycuts out only part of a tumour
    • excisionalcuts out the whole tumour.

    At the laboratory, a specialist doctor called a pathologist will run a series of stains on the sample to see if they can work out the type of cancer. These stains may show specific changes in the cells or highlight proteins (antigens) that are linked to various types of cancer. It may be a week or more before results are available.

    Some labs can test a biopsy for genetic changes or patterns linked to specific types of cancer. These may be called cytogenetic tests or gene expression-based profiling (GeBP). As it is not yet clear how useful these tests are, their availability is still limited.

    Endoscopy

    This procedure is used to look inside the body for any abnormal areas. A thin, flexible tube with a light and camera on the end, called an endoscope, is inserted through a natural opening (such as the mouth, anus or vagina) or through a small cut made by the surgeon. The endoscope has a small cutting instrument on the end so a biopsy can be taken at the same time if something suspicious is seen. The most common types of endoscopies are listed in the table below.

    Imaging tests

    This website page was last reviewed and updated February 2018.

    Information reviewed by: A/Prof Linda Mileshkin, Medical Oncologist, Peter MacCallum Cancer Centre, VIC; Dr Sarwan Bishnoi, Medical Oncologist, Adelaide Cancer Centre, SA; Dave Clark, Consumer; Dr Jan Maree Davis, Area Director, Palliative Care Service, Calvary Health Care and St George Hospital, NSW; Linda Tompsitt, Cancer Nurse 13 11 20, Cancer Council WA; Catherine Trevaskis, Gastrointestinal Cancer Specialist Nurse, The Canberra Hospital, ACT

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