This information is about cancer of unknown primary (CUP). Cancer of unknown primary is a diagnosis used when doctors are not able to find where a cancer first starts.

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What is advanced cancer?

Advanced cancer (also called secondary cancer or metastatic cancer) is cancer that has spread from the part of the body where it started (the primary cancer), to another part of the body.

Although the cancer is growing in a different part of the body, it is still named after the primary cancer.  For example, if breast cancer has spread to the bone, it is called advanced breast cancer. 

Cancer of unknown primary

Sometimes, doctors cannot find where in the body cancer started (primary cancer), but they do find cancer that has spread. 

This is called cancer of unknown primary (CUP). 

There are different reasons why a primary cancer cannot be found.  For example:

  • The primary cancer is very small.
  • The body’s immune system destroyed the primary cancer.
  • The cancer has spread to many parts of your body and it’s not clear where it first started.
  • The primary cancer was removed during surgery for another reason and the doctors did not know the cancer was there.

Your treatment team may use different words to describe cancer of unknown primary.

You may hear it called:

  • metastatic cancer (mets)
  • secondary cancer
  • stage 4 (IV) cancer.

Symptoms of cancer of unknown primary

Symptoms of cancer of unknown primary depend on where the cancer has spread to. 

Some symptoms you might want to get checked include:

  • a lump on any part of your body
  • pain that is in one part of your body and does not go away
  • a cough that does not go away
  • a change in bowel or bladder habits
  • recurring fever for no reason
  • night sweats
  • fatigue – extreme tiredness that doesn’t go away with rest
  • losing weight without trying.

Having these symptoms does not mean you have cancer, but it is important to get any changes checked by your doctor.

Finding out if you have cancer of unknown primary

If your GP or whānau doctor is concerned that any symptoms you have could be caused by cancer that has spread, they will recommend further tests (investigations).

Sometimes, the part of the body where the cancer cells are first found helps the doctors to decide what tests will be most helpful. 

  • When cancer is found above the diaphragm (the muscle under the lungs that helps with breathing), the primary cancer is likely to be in the upper part of the body such as the lung or breast.
  • When cancer is found below the diaphragm, the primary cancer is likely to be in the lower part of the body such as the pancreas or liver.

These tests may include:

A biopsy takes a small sample of the abnormal cells to check if they contain cancer.

You may have blood tests to check your general health.

A CT scan creates a 3D picture of the inside of your body. It can show smaller cancers than an x-ray can.

Endoscopy uses a long, thin, flexible tube with a small camera and light at the end, to look inside different parts of the body. It is most often used to look at parts of the digestive system including the oesophagus (food pipe), stomach and bowel.

A mammogram is an X-ray of your breast.

An MRI uses magnets and radio waves to make a detailed picture of the inside of your body.

A PET-CT scan uses a radioactive dye injected into your arm that will show up in areas affected by cancer. You may have to go to another hospital for this scan.

A tumour marker is a substance that might be raised if there is a cancer.  Tumour markers can be found in the blood, urine (wee) or body tissues. 

For example:

  • Cancer antigen 125 (CA125) may be found in higher levels in ovarian cancer and other gynaecological cancers
  • Carcinoembryonic antigen (CEA) may be found in higher levels in bowel cancer.
  • Prostate specific antigen (PSA) may be found in higher levels in prostate cancer.
  • Cancer antigen 19-9 (CA19-9) may be found in higher levels in pancreatic cancer
  • Cancer antigen 15-3 (CA15-3) may be found in higher levels in breast cancer

Managing cancer of unknown primary

Because cancer of unknown primary is considered an advanced cancer, treatment is unlikely to cure your cancer.  The goals of any treatments are to control the cancer for as long as possible, improve any symptoms you may be experiencing, and to maintain your quality of life.

Your treatment may include:

Sometimes treatments for cancer, such as radiation or chemotherapy, may no longer work, but you will always benefit from supportive care.

Supportive care includes the management of physical symptoms, emotional and spiritual support, and guidance to help you plan for the future.

Supportive care will mostly be provided by your primary health care team, Cancer Society support workers, and specialist palliative care services.

If the symptoms you are experiencing are difficult to manage, you and your whānau may be referred to a specialist palliative care service.

Specialist palliative care helps with the physical and emotional needs of people with advanced cancer and can link you with practical support in your local area.  Care can be provided at home or in a hospital, rest home, or hospice by doctors, nurses, social workers, spiritual care workers, and cultural health services.

Living well with advanced cancer

Looking for ways to stay as well possible can help reduce stress and improve your wellbeing.

The following suggestions may be helpful:

  • Eating well, keeping active and relaxing can help your overall health and improve sleep.
  • Keeping in touch with whanau and friends can be an important support. You may choose to keep working if you can - talk to your employer about reduced hours or lighter duties if you need.
  • Some people find that praying or talking to a spiritual advisor/tohunga is a way to find strength and meaning in times of stress.
  • Setting goals for things you have wanted to do but have not yet had the chance can give a sense of structure and purpose.

Learning to manage uncertainty is another important part of staying healthy.

These tips may help:

  • It is important to ask for support. Talk with your treatment team about support and resources available to help you if you are struggling.
  • Accept that there are things you can control and things you cannot.
  • Talk to the Cancer Society or your GP about counselling services.
  • Try a local support group or talk with a social worker at the hospital.
  • Talk with family/whānau and friends. Tell them how you are feeling and how they can help.
  • Learn as much as you can about the cancer and its treatment. Having the right information can help you know what to expect.
  • Maintain your usual interests, friendships, and activities that give you time out from cancer.
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Last updated: May 30, 2023