Tests and scans for CUP

Your doctor may need to do a series of tests to find out more about the cancer. One of the most important tests is a biopsy. This is when a small sample of cells is removed from the secondary cancer and examined under a microscope. If it is not clear what type of cell it is, further tests can be done to find out more. There are different types of biopsy.

Sometimes a biopsy might not be possible. This could be because the cancer is too difficult to reach or someone is too unwell.

You will also usually have a CT (computerised tomography) scan and an MRI (magnetic resonance imaging) scan. You may also have an ultrasound scan. These scans build up a picture of the inside of your body. They may also be used to help take a sample of cells in a biopsy.

It can take up to two weeks to get your results. Waiting for these can be difficult. It can help to talk about your worries with someone close to you.

About tests

We don’t list all the possible tests you may have, but we’ve included those most likely to be used, depending on your symptoms. The hospital staff will give you information about how to prepare for any tests and what to expect.

X-rays and scans are often done before more specific tests. They can check your lungs or other parts of the body, such as the bones.


One of the most important tests is a biopsy. This helps your doctor find out more about the type of cell the cancer developed from.

Your specialist will remove a small sample of tissue or cells (biopsy) from the secondary cancer. They may sometimes use a scan or ultrasound to help guide a biopsy needle to the exact area. Tests are then done on the cells from the biopsy. It is not always possible to do a biopsy. Sometimes the cancer is too difficult to reach or a person is too unwell. Your specialist will discuss this with you and arrange other tests if you need them.

There are different types of biopsy. Your specialist will explain which is best for you.

Fine needle aspiration (FNA) biopsy

This is a quick, simple procedure that can be done in the outpatient clinic. The doctor puts a fine needle into the lump and removes a few drops of fluid, containing a sample of cells. You may have a local anaesthetic to numb the area where the needle goes in.

Core biopsy

This test is similar to an FNA but uses a slightly larger needle. A core biopsy removes a larger amount of tissue than an FNA, which can be more helpful with diagnosis. You will have a local anaesthetic injection into the skin, to numb the area first. It is usually done in an outpatient clinic.

Excisional biopsy

If a lump or suspicious area is small enough, it can sometimes be completely cut out (excised) by a surgeon. For example, if you have a swollen lymph node, the whole node is removed.

Removing the whole lump means the doctors have as much tissue as possible to help them to make the diagnosis.

If the lump is near the surface, it is normally a simple operation to remove it using a local anaesthetic. If the lump is deeper in the body, you will usually have a general anaesthetic and may need to stay in hospital overnight.

If the lump is very deep in the body and would need major surgery to remove it, your specialist may try a core or FNA biopsy first.

Sometimes the lump can be removed using an endoscope.

Incisional biopsy

This procedure is similar to an excisional biopsy, but only part of the lump or tumour is removed. This is used when the lump is large and it would be too complicated to remove it all.

Removing fluid for testing

Some people have a build-up of fluid around the lung, called a pleural effusion. Or they may have a collection of fluid around the tummy (abdomen) known as ascites. A sample of the fluid can be taken to check for cancer cells.

You will have an injection of local anaesthetic to numb the area. Then a small needle will be put through the skin into the fluid. Some fluid is taken out using a syringe and is examined under a microscope. Sometimes an ultrasound is used to help find the best area to put the needle into.

Removing fluid from the chest is called thoracentesis. Removing fluid from the abdomen is called paracentesis.

Bone marrow sample

Your specialist may check whether the cancer is affecting the bone marrow. This is a spongy material that fills some of our bones and produces blood cells.

A small sample of bone marrow is taken from the back of the hip bone (pelvis) or occasionally the breast bone (sternum). The doctor puts a thin needle through the skin into the bone and takes a sample of the bone marrow. You will have a local anaesthetic to numb the area.

You may feel bruised and ache for a few days after having the sample taken. Mild painkillers can help with this.

Not everyone will need to have a bone marrow sample taken. If this test is likely to be useful in your situation, your doctor or specialist nurse will explain the procedure in more detail.

Examining the cells under a microscope

A doctor called a pathologist will examine the sample to try to identify the type of cell and where in the body it first developed. If the diagnosis isn’t clear, more tests can be done on the cells.

Immunohistochemistry tests

This test finds out whether there are particular proteins (antibodies) on the surface of the cell. This can sometimes give an idea of what type of cancer it is.

Cytogenetic tests

These look at the changes in the chromosomes in a cell. Chromosomes are made up of genes. Genes control how a cell grows and behaves. Changes in the structure of some chromosomes can be linked to certain cancers.

Hormone and protein receptors

Some cancer cells have receptors, which allow particular types of hormones or proteins to attach to the cancer cell. The biopsy sample can be tested to see whether receptors are present. This may help doctors find out where the cancer cells came from.

Gene expression-based profiling (GeBP)

Every cell type in our body has a unique genetic pattern. Research is looking at new ways of identifying genetic patterns in cancer tissue. This is called gene expression-based profiling. The tests look at the patterns of genes in the secondary tumour, to try to find out the primary cancer.

At the moment, it’s not clear how helpful these techniques are or how best to use them. The results may help to narrow down which possible type of cancer it is and may help doctors decide the best tests and treatments to try.

As more research is needed to confirm the benefits of GeBP, this type of test is not routinely available on the NHS. But you may be asked to take part in a clinical trial. We have more information about taking part in a clinical trial.

CT (computerised tomography) scan

A CT scan takes a series of x-rays, which build up a three-dimensional picture of the inside of the body. The scan takes 10 to 30 minutes and is painless. It uses a small amount of radiation, which is very unlikely to harm you and will not harm anyone you come into contact with.

CT scan
CT scan

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You may be given a drink or injection of a dye, which allows particular areas to be seen more clearly. This may make you feel hot all over for a few minutes. It is important to let your doctor know if you are allergic to iodine or have asthma, because you could have a more serious reaction to the injection.

You will probably be able to go home as soon as the scan is over.

PET-CT scan

This is a combination of a CT scan, which takes a series of x-rays to build up a three-dimensional picture, and a positron emission tomography (PET) scan. A PET scan uses low-dose radiation to measure the activity of cells in different parts of the body.

PET-CT scans give more detailed information about the part of the body being scanned. You may have to travel to a specialist centre to have one. You cannot eat for six hours before the scan, although you may be able to drink. A mildly radioactive substance is injected into a vein, usually in your arm. The radiation dose used is very small. You will wait for at least an hour before you have the scan. It usually takes 30 to 90 minutes. You should be able to go home after the scan.

MRI scan

An MRI scan uses magnetism to build up a detailed picture of areas of your body. The scanner is a powerful magnet so you may be asked to complete and sign a checklist to make sure it is safe for you. The checklist asks about any metal implants you may have, such as a pacemaker, surgical clips or bone pins, etc.

You should also tell your doctor if you have ever worked with metal or in the metal industry as very tiny fragments of metal can sometimes lodge in the body. If you do have any metal in your body, it is likely that you will not be able to have an MRI scan. In this situation, another type of scan can be used. Before the scan, you will be asked to remove any metal belongings including jewellery.

Some people are given an injection of dye into a vein in the arm, which does not usually cause discomfort. This is called a contrast medium and can help the images from the scan to show up more clearly. During the test, you will lie very still on a couch inside a long cylinder (tube) for about 30 minutes. It is painless but can be slightly uncomfortable, and some people feel a bit claustrophobic. It is also noisy, but you will be given earplugs or headphones. You can hear, and speak to, the person operating the scanner.

Ultrasound scan

Ultrasound scans use sound waves to build up a picture of the inside of the body. A gel is spread on to the skin and a small device is passed over the area. A picture of the area is then shown on a screen. An ultrasound only takes a few minutes and is sometimes used to guide a biopsy.

If you have a pelvic ultrasound, you will be asked to drink plenty of fluids so your bladder is full. This helps to give a clearer picture. Some women have a vaginal ultrasound instead of a pelvic one and you don’t need to have a full bladder for this.

Waiting for test results

Waiting for test results can be a difficult time. It may take from a few days to a couple of weeks for the results of your tests to be ready. You may find it helpful to talk with your partner, family or a close friend. Your specialist nurse or one of the organisations listed on our database, can also provide support. You can also talk things over with one of our cancer support specialists on 0808 808 00 00.

Back to Diagnosing

Being diagnosed with CUP

If your GP thinks you may have cancer, they will refer you to hospital for more tests. You may be referred to a specialist CUP team.