Testing genes to see if cancer is likely to come back
This page is about testing genes in cancer cells to see how likely the cancer is to come back. There is information about
These gene tests are a way of looking at the genes in cancer cells to try and see how likely it is that the cancer will come back in the future.
You may hear your doctor call this type of test a gene expression profiling (GEP) test, a gene expression analysis test, or a gene assay. Here, we’ll call them GEP tests, so it is clear which tests we’re talking about. Two you may have heard of are the Oncotype DX test and the MammaPrint test which are tests for breast cancer.
GEP tests look for abnormalities in gene activity within cancer cells, not genes in normal body cells. So they are different to tests looking for an inherited faulty gene that increases a person’s risk of getting cancer in the first place. We have information about genetic testing in our section about genes and inherited cancer risk.
The GEP tests are also different to other tests you may have heard about that show whether your cancer is likely to respond to a particular drug. This is generally known these days as personalised medicine. The GEP tests are a step towards personalised medicine, in that they help a doctor to decide who needs further treatment in general. But the personalised medicine tests show if cancer cells have a particular protein that means a specific drug is likely to work. An example of this is the Her2 test, which is a test for breast cancer and shows whether your breast cancer is likely to respond to Trastuzumab (Herceptin).
You may also have heard about a research study called METABRIC. This study, funded by Cancer Research UK, has been looking at other changes in the genes of breast cancer cells. Recently published, the research shows that there are at least 10 different sub types of breast cancer. These subtypes are based on the particular gene changes in the breast cancer cell. The researchers hope that in the future this information will help doctors to decide how much treatment each person needs and which types of treatment their cancer is most likely to respond to.
Research is at an early stage and general tests for gene changes are not available at the moment. It will be some years before this information changes the treatment people have for breast cancer. You can find out more about this study on our science blog.
GEP tests look at groups of cancer genes to find out how active they are. The activity of particular genes may be able to help doctors to predict whether a cancer is likely to come back. Looking at the genes helps a cancer specialist to decide who needs extra treatment to lower the risk of their cancer coming back.
For example, if the chance of the cancer coming back after surgery and radiotherapy is low, you may not need to have treatment with chemotherapy. If the chance of the cancer coming back is higher, your doctor will suggest that you have chemotherapy.
Knowing the chance of the cancer coming back helps the doctor to give some patients treatment they need and avoid giving other patients treatment they don’t need. It is important that people don’t have unnecessary treatments, because all treatment will have some side effects.
In many cases, it will be clear to a specialist whether a patient definitely needs further treatment, or definitely doesn’t. So these tests may be most useful where there is some uncertainty about your risk of the cancer coming back.
Two main tests have been developed for breast cancer. There are others in development. The 2 tests already developed are called
There is more information about both of these tests below. They are both carried out on the cancer after it has been removed with surgery. Doctors send a sample to a laboratory in the USA for the Oncotype DX test and to the Netherlands for the MammaPrint test. It takes between 7 and 10 days for the results to come back.
The National Institute for Health and Clinical Excellence (NICE) has assessed these tests. It recommends that the Oncotype DX test should be an option to help make decisions about whether people with an intermediate grade cancer need chemotherapy after surgery. NICE says we need more research before they can recommend the other tests.
The test is for people with
- Stage 1 or 2 breast cancer
- No cancer cells in the lymph nodes
- Oestrogen receptors in their cancer cells
- HER2 negative cancer - this is a protein that some cancer cells have
The Oncotype DX test looks at a group of 21 genes in the cancer cells to find out how they are behaving. The cancer is then given a recurrence score of between 0 and 100. The lower the number is, the lower the risk is of the cancer coming back. The higher the number, the higher the risk. People with a higher score have chemotherapy and those with a low score don’t.
This test looks at a group of 70 genes. It is for people with
- Stage 1 or 2 breast cancer
- Cancer cells in 0 to 3 lymph nodes
- Any level of oestrogen receptors in the cancer cells
The Mammaprint test gives an idea of whether people have a low risk or high risk of the cancer coming back.
GEP tests are not widely available and are still used mainly within research. They are still in the early stages of development for most types of cancer. It takes time for scientists to develop these tests, to make sure that they work, and that they are accurate and cost effective.
The tests have to be different for each type of cancer because the gene activity in the cells of a breast cancer is different to the cells of a bowel cancer, for example. And within the same type of cancer it may also be necessary in the future to develop different tests for different stages of the cancer.
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