Waiting for the results of these tests can be stressful. It might take several days, or even two or three weeks, for a definitive diagnosis. But the more information your team has, the better they'll be able to put together the best treatment plan for your child.
If you, or they, are unsure about why a particular test is being done or have any questions about how it will be carried out, you may want to talk to your specialist or one of your child's medical team.
These tests are most commonly used for diagnosing cancer:
A biopsy involves removing a small part of a lump or tumour, either with a specially designed needle (needle biopsy) or during a small operation (open biopsy). The sample is then examined and tested in a laboratory to determine what type of tumour it is. Most suspected tumours will be biopsied.
In a bone marrow test, a needle is inserted into the bone to collect some of the bone marrow. Your child may have a sedative to make them drowsy, or a general anaesthetic to make them sleep. If they are not having a general anaesthetic, the area will be numbed first using local anaesthetic.
The bone marrow sample is checked in a lab to see if there are any abnormal changes that suggest cancer. This test might also be repeated to monitor your child’s condition once they have a diagnosis.
Blood tests are usually done before, during and after treatment. Some of the reasons for blood tests include:
- Detecting cancer
- Checking for infection
- Monitoring how well treatment is working
- Monitoring the side effects of treatment
- Making sure your child’s body’s systems (such as the liver or kidneys) are still working properly
- Matching your child’s blood with a donor’s if they need a transfusion
- Monitoring your child’s blood count (the number of red and white blood cells and platelets in their blood).
A reduction in the total number of blood cells is a common side effect of treatment.
A lumbar puncture is used to test the fluid around the spinal cord (called the cerebrospinal fluid) to see if it contains cancer cells. A needle will be inserted between the bones in the lower spine, and a few drops of the fluid will be drawn out for analysis. This is usually done under general anaesthetic. As some people have a headache afterwards, your child may be asked to lie flat for a while once they have had the test, to try and prevent a headache coming on.
A lumbar puncture is used when leukaemia, lymphoma and some solid tumours are suspected or confirmed. It tests whether the cancer has spread to this fluid from elsewhere in the body.
X-rays can help to diagnose a suspected tumour in the chest or bones. X-rays are also used at other times, for example, to check for a chest infection if your child has a temperature.
Sometimes tumour tissue can look very different to healthy tissue on an X-ray, but this is not always the case. If the tumour tissue is not obvious on an X-ray, the specialists may need to use different scans to get a more detailed picture.
A computerised tomography (CT) scan uses X-rays to produce images of the inside of the body. Your child will need to lie very still during the scan, but it only takes a few minutes. Younger children may be given a sedative or general anaesthetic. Sometimes an injection is also given with the scan to help different areas of the body show up more clearly.
A magnetic resonance imaging (MRI) scan involves lying in a narrow tunnel within the machine as the scan takes place. The scanner uses magnetic waves to create a detailed image of the inside of your child's body.
The machine can be noisy, so older children may want to play music through headphones to help them relax and stay very still. Younger children may be given a sedative or general anaesthetic. The scan will usually last between 20 and 60 minutes, depending on the parts of the body that need scanning.
An ultrasound scan uses sound waves to look at different organs inside the body, especially the heart, liver or kidneys. It can reveal the presence of unhealthy tissue. The person doing the scan will put some gel on your child’s skin, which may feel a little cold. They will then move a hand-held ultrasound wand around, pressing it over the part of the body that is being scanned.
A bone scan highlights areas of the bone that are growing or changing rapidly. It starts with a radioactive fluid (called a tracer) being injected into your child's vein. This will then travel to their bones. They will then have a scan of their whole skeleton and the tracer shows up. The results can help to tell if cancer is affecting any of your child’s bones.
This is a scan used to diagnose neuroblastoma. A radioactive substance is injected into the vein, which is then taken up by the tumour cells. Your child will need to take medicines to protect their thyroid gland in the days before the scan.
Your child will be asked to lie still on a bed and various X-ray pictures will be taken from above and below them. Younger children may need sedation or a general anaesthetic to help them with the test. Older children will be encouraged to listen to music or watch a DVD to help them stay still.
- If your child is old enough, they may want to look at our advice and factsheets for teenagers and young adults about diagnosis and tests
- Read our digestible information about different cancer types
- Find out more about treatments for cancer
Updated November 2017, next review due 2019.