Further tests after diagnosis

You will have tests to find out the size and position of the cancer, and whether it has spread. This is called staging. It will help you and your doctor make decisions about your treatment.

Your blood may be tested for a protein called carcinoembryonic antigen (CEA). If the level of CEA is high, your doctors will check it regularly to see how well your treatment is working.

You will have a CT scan, which uses x-rays to see whether the cancer has spread outside the bowel. If your doctor needs more information after a CT scan, they may organise a PET/CT scan. This uses low-dose radiation to identify areas of cancer. If there is cancer in the liver, you may have an MRI scan. This uses a magnet to build a picture of the inside of your body.

It may take up to two weeks for all your test results to be ready. This can be a stressful time. You may find it helpful to talk about your worries with someone close to you.

Further tests

If any of your biopsies show that there is cancer in the bowel, you will have more tests. These are to find out the size and position of the cancer and whether it has spread. This is called staging.

The results will help you and your doctor decide on the best treatment for you. Some tests may be repeated during and after treatment to check your progress. Your doctor or specialist nurse will explain this to you.

The tests you may have include:

  • blood tests to assess your general health
  • a CT scan to check for any signs that the cancer has spread outside the bowel
  • a PET/CT scan if more detailed information is needed or if there is cancer in the liver or lungs
  • an MRI scan if there is cancer in the liver.


Blood tests

Your blood may be tested for a protein called carcinoembryonic antigen (CEA). Some people with bowel cancer have higher levels of this protein. If your level of CEA is high, your doctors may check it regularly to see how well your treatment is working.


What happens in a CT 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 10–30 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. You will be asked not to eat or drink for at least four hours before the scan.

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’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.

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


PET/CT scan

This is a combination of a CT scan (see above) 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.

A PET/CT scan may occasionally be done if more detailed information is needed after a CT scan. It may also be used to help the doctors plan treatment if there is cancer in the liver or lungs.

You won’t be able to eat for six hours before the scan, although you may be able to drink. A technician injects a small amount of mildly radioactive glucose (sugar) into a vein in your hand or arm. The radiation dose is very small. You then wait for the glucose to be absorbed by your body. After an hour or so you have the scan, which takes 30–90 minutes. The scan will show areas where the glucose has been absorbed. Cancers absorb more glucose than other parts of the body. This helps the doctors identify any areas of cancer. You can usually go home after the scan.


MRI scan

This test 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's safe for you. The checklist asks about any metal implants you may have, such as a pacemaker, surgical clips, bone pins, etc. 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.


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.

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