Further tests for bowel cancer
If any of the general tests or tests to find cancer in the bowel show you have bowel cancer, you will have more tests to see if the cancer has spread to other parts of your body. Before any test, ask how much you will have to pay.
Learn more about these additional tests:
Your blood may be tested for a protein produced by some cancer cells. This is called a tumour marker. The most common tumour marker for bowel cancer is called carcinoembryonic antigen (CEA). If the results of the blood test show that you have a high CEA level, your doctor may organise more tests. This is because other factors, such as smoking or pregnancy, may also increase the level of CEA. If your CEA level is high, it will be retested after treatment to see if it has returned to normal. Not all bowel cancers have a raised CEA.
A CT (computerised tomography) scan uses x-rays and a computer to create a detailed picture of the inside of the body. CT scans are usually done at a hospital or radiology clinic. When you make the appointment for the scan, you will be given instructions to follow about what you can eat and drink before the scan.
As part of the procedure, a dye is injected into a vein to make the pictures clearer. This dye may make you feel hot all over and leave a strange taste in your mouth for a few minutes. You might also feel that you need to urinate (wee or pee), but this sensation won’t last long.
During the scan, you will need to lie still on a table that moves in and out of the CT scanner. Your chest, abdomen and the area between your hip bones (pelvis) will be scanned to see if the cancer has spread to these areas. The scan itself takes 5–10 minutes and is painless.
Before having scans, tell the doctor if you have any allergies or have had a reaction to dyes during previous scans. You should also let them know if you have diabetes or kidney disease, are pregnant or breastfeeding, or are claustrophobic (afraid of confined spaces).
An MRI (magnetic resonance imaging) scan uses a powerful magnet and radio waves to create detailed pictures of the inside of your body.
Usually only people with cancer in the rectum have an MRI; it is not commonly used for cancers higher in the bowel. An MRI may also be used to scan the liver if an abnormality seen on a CT scan needs further investigating.
Before the scan, let your medical team know if you have a pacemaker or any other metallic object in your body. If you do, you may not be able to have an MRI scan as the magnet can interfere with some metallic objects. Newer devices are often safe to go into the scanner.
Before the MRI, you may be injected with a dye to help make the pictures clearer. During the scan, you will lie on an examination table that slides into a large metal tube that is open at both ends.
The noisy, narrow machine makes some people feel anxious or claustrophobic. If you think you could become distressed, mention it beforehand to your medical team. You may be given a medicine to help you relax and you will usually be offered headphones or earplugs.
The scan may take 30–90 minutes, depending on the size of the area being scanned and how many images are taken.
A positron emission tomography (PET) scan combined with a CT scan is a specialised imaging test. The 2 scans provide more detailed and accurate information about the cancer. A PET–CT scan is most commonly used before surgery to help find out where the cancer has spread to in the body. It can also be used after surgery to check if the cancer has come back after treatment.
When you make the appointment for the scan, you will be given instructions to follow about how to prepare for the scan, including what you can eat and drink.
Before the scan, you will be injected with a glucose solution containing a small amount of radioactive material. Cancer cells show up brighter on the scan because they take up more glucose solution than the normal cells do. You will be asked to sit very quietly for 30–90 minutes as the glucose spreads through your body, then you will be scanned. The scan itself will take around 30 minutes. Let your doctor know if you are claustrophobic as the scanner is a confined space.
Medicare covers the cost of PET–CT scans for bowel cancer only in limited circumstances. If this test is recommended, check with your doctor what you will have to pay.
If you are diagnosed with bowel cancer, the biopsy sample or the tissue removed during surgery will usually have more tests. Called molecular tests, they look for gene changes (mutations) and other features in the cancer cells that may be causing them to multiply and grow.
Your treatment team uses the results of molecular testing to tell them what treatment may work for you and which treatment may not work.
For example, some targeted therapy drugs do not work for people with a RAS gene mutation. Immunotherapy drugs also only work for people with a fault in the gene that helps the cell’s DNA repair itself (called mismatch repair or MMR genes). See Drug therapies for more details.
Podcast: Tests and Cancer
A/Prof David A Clark, Senior Colorectal Surgeon, Royal Brisbane and Women’s Hospital, QLD, The University of Queensland and The University of Sydney; Yvette Adams, Consumer; Dr Cameron Bell, Gastroenterologist, Royal North Shore Hospital, NSW; Katie Benton, Advanced Dietitian Cancer Care, Sunshine Coast University Hospital and Queensland Health, QLD; John Clements, Consumer; Dr Fiona Day, Medical Oncologist, Calvary Mater Newcastle, NSW; Alana Fitzgibbon, Clinical Nurse Consultant, GastroIntestinal Cancers, Cancer Services, Royal Hobart Hospital, TAS; Prof Alexander Heriot, Consultant Colorectal Surgeon, Director Cancer Surgery, Peter MacCallum Cancer Centre, and Director, Lower GI Tumour Stream, Victorian Comprehensive Cancer Centre, VIC; Caitriona Nienaber, 13 11 20 Consultant, Cancer Council WA; Dr Kirsten van Gysen, Radiation Oncologist, Nepean Cancer Care Centre, NSW.
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