Further tests for cancer of unknown primary
Your specialist will usually arrange for you to have some of these tests. In some people, these tests will diagnose the primary cancer.
We can’t list all the possible tests you may have here, but we’ve included those most likely to be used depending on your symptoms. You’ll be given information by your hospital about how to prepare for any tests and what to expect.
These are taken to check your lungs or other parts of the body, such as the bones.
CT (computerised tomography) scan
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A CT scan takes a series of x-rays, which build up a three-dimensional picture of the inside of the body. It is often used to investigate CUP. The scan takes 10-30 minutes and is painless. It uses some radiation, which is very unlikely to harm you and will not harm anyone you come into contact with.
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’s 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.
MRI (magnetic resonance imaging) scan
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This test uses magnetism to build up a detailed picture of areas of your body. It’s sometimes used to look for a cancer in the breast if there is cancer in the lymph nodes in the armpit.
The scanner is a powerful magnet so you may be asked to complete and sign a checklist to make sure it’s safe for you. The checklist asks about any metal implants you may have, for example a pacemaker, surgical clips and bone pins. You should also tell your doctor if you’ve 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’s likely that you won’t be able to have an MRI scan. In this situation another type of scan can be used.
Before the scan, you’ll be asked to remove any metal belongings including jewellery. Some people are given an injection of dye into a vein in the arm, which doesn’t 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’ll lie very still on a couch inside a long cylinder (tube) for about 30 minutes. It’s painless but can be slightly uncomfortable, and some people feel a bit claustrophobic. It’s also noisy, but you’ll be given earplugs or headphones. You can hear, and speak to, the person operating the scanner.
This is a combination of a CT scan and a PET (positron emission tomography) scan. It may be used to look for a primary cancer in the head and neck area if there is cancer in the lymph nodes in the neck. It’s not clear how useful it is in other situations when CUP is suspected.
PET scans use 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. They are a new type of scan and you may have to travel to a specialist centre to have one.
A mildly radioactive substance is injected into a vein, usually in your arm. The radiation dose used is very small. The scan is done about an hour later. It usually takes 30-90 minutes.
Ultrasound scans use sound waves to build up a picture of organs such as the abdomen, liver and pelvis. A gel is spread onto the skin and a small device is passed over the area. This shows a picture of the area on a screen. An ultrasound only takes a few minutes and is also sometimes used to guide a biopsy.
If you have a pelvic ultrasound you’ll be asked to drink plenty of fluids so your bladder is full. This helps to give a clear picture. Some women have a vaginal ultrasound instead of a pelvic one. This gives a better picture and you won’t need to have a full bladder.
During an endoscopy, an endoscope - a thin flexible tube with a camera at the end - is used to look inside the gullet, stomach, small bowel or large bowel. The endoscope also has a small cutting instrument on the end that allows the doctors to take biopsies of any abnormal areas. During the test some air may be pumped through the endoscope to make the area easier to see.
Before the test you may be given a sedative to help you relax and make you feel sleepy.
Upper body endoscopy
You’ll be asked to lie on your side on a couch. The doctor or nurse will ask you to swallow the first part of the endoscope. They will then gently ease it further down your gullet and into your stomach. When the test is over the endoscope is gently pulled out.
Lower body endoscopy
You’ll be asked to lie curled up on your left side while a tube is gently passed into your back passage. The procedure is called a sigmoidoscopy when the lower part of the bowel is examined and a colonoscopy when the whole bowel is looked at.
A doctor or specially trained nurse uses a thin flexible tube with a camera on the end of it (bronchoscope) to examine the inside of the lung airways and take samples of tissue (biopsies). You may be given a mild sedative to help you relax. A local anaesthetic is sprayed on the back of your throat to numb it. The bronchoscope is then gently passed into your nose or mouth and down into the lung airways. The test may be slightly uncomfortable but it only takes a few minutes.
Video-assisted thoracoscopic surgery (VATS)
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This is a small operation that uses keyhole surgery to examine the surface of the lung and take biopsies. It may be done when a bronchoscopy is negative and a biopsy can’t be taken through the skin.
A mammogram is a low-dose x-ray of the breast. In CUP it’s done if a woman has symptoms of breast cancer, such as cancer in the lymph nodes in the armpit. The radiographer (person who takes the x-ray) will position you so your breast is against the x-ray machine and gently compressed with a flat, clear, plastic plate. Two mammograms (from different angles) are taken of each breast.
Most women find having a mammogram uncomfortable or a bit painful, but the test doesn’t take long.
You’ll also have tests done on your blood and your urine.
These are done to check:
how organs such as your liver and kidneys are working
the number of different blood cells you are producing (blood count).
A low number of red blood cells (anaemia) may mean that there’s some bleeding inside your body, possibly from a cancer in the bowel or stomach. Lots of changes to the blood cells may mean that a cancer is affecting the bone marrow where blood cells are made.
Some cancers produce chemicals that can be measured in the blood called tumour markers. These can also be raised in conditions other than cancer, so they aren’t always reliable.
Tumour markers aren’t usually measured in CUP. In certain situations the following may be measured:
PSA (prostate specific antigen) to check for prostate cancer.
Alpha-fetoprotein (AFP) or human chorionic gonadotrophin (HCG) to check for testicular cancer.
Alpha-fetoprotein (AFP) to check for a primary liver cancer.
CA125 to check for ovarian cancer.
Urine tests (urine cytology)
Samples of your urine can be tested for abnormal cells and to see how well your kidneys or bladder are working. Rare cancers, such as neuroendocrine cancers, produce extra hormones that can be measured in the urine. Your urine may be collected over 24 hours to check this.
FOB (faecal occult blood) test
A small sample of your stool (faeces) can be tested for tiny amounts of hidden blood that can’t be seen by the naked eye.