Tests on your breast cancer cells
After a breast biopsy or surgery, a sample of tissue is sent to the laboratory. A doctor called a pathologist does various tests on the tissue. The tests help to diagnose breast cancer. They can also:
- show which type of breast cancer you have
- look for proteins on the surface of the breast cancer cells. These are hormone receptor (oestrogen receptor and progesterone receptor) and HER2 receptor tests
The pathologist may also do other tests in the laboratory such as tests to look at cancer 
to find out how active they are. These are called tumour profiling tests such as the Oncotype Dx test.
All this information helps your doctor decide on the best treatment for you.
Finding the type of breast cancer you have
A pathologist looks at the tissue under a microscope to see which type of breast cancer it is. They can tell this by the shape of the cells and the pattern of the cells in the breast tissue.
There are different types of breast cancer. The most common type is invasive breast cancer (no special type or NST).
Hormone receptor tests
Most breast cancers have proteins (receptors) for . They are called oestrogen receptor positive or ER positive (ER+) breast cancer. Around 80 out of every 100 breast cancers (around 80%) are oestrogen receptor positive.
Breast cancers that have very low levels of oestrogen or no oestrogen receptors are called oestrogen receptor negative or ER negative (ER-) breast cancers.
Some breast cancers also have receptors for . These are progesterone receptor positive or PR positive breast cancers.
is only likely to work for cancers that are oestrogen receptor positive. This is because hormone therapies work by stopping oestrogen from stimulating the cancer cells to grow and divide.
HER2 receptor tests
Some breast cancers have large amounts of a protein called HER2. HER2 stands for human epidermal growth factor 2.
Breast cancers that have large amounts of HER2 are called HER2 positive breast cancers. About 15 out of every 100 breast cancers (about 15%) are HER2 positive.
Testing breast cancer cells for the HER2 protein can help to show whether targeted drugs might work. Targeted cancer drugs are treatments that change the way cells work and help the body control the growth of cancer. The drugs attach to the HER2 protein and stop the cells from growing and dividing.
Triple negative breast cancer
Triple negative breast cancers don't have oestrogen, progesterone or HER2 receptors. Around 15 out of 100 breast cancers (around 15%) are triple negative breast cancer. It is more common in younger women.
Hormone therapies and HER2 targeted cancer drugs do not work well for this type of breast cancer. So you are more likely to have chemotherapy.
Tumour profiling tests for breast cancer
Tumour profiling tests are also called gene expression profiling tests (GEP tests) or gene assays. The results of these tests can help your doctor:
- decide the best treatment for you after surgery for early breast cancer
- predict whether a cancer is likely to come back
There are different types of tumour profiling tests available for breast cancer. They include:
- EndoPredict (EPclin score)
- Oncotype DX Breast Recurrence Score
- Prosigna
How tumour profiling tests for breast cancer work
Tumour profiling tests look at groups of cancer to find out how active they are. The activity of particular genes helps the doctor predict whether a cancer is likely to come back or not. This can help them decide who needs extra treatment to lower the risk of their cancer coming back.
For example, you might not need to have chemotherapy if the risk of the cancer coming back after surgery is low. It is important that people don’t have unnecessary treatments because all treatments have some side effects.
Doctors can also use computer tools such as the Predict breast cancer tool to help them decide the best treatment for you.
Who can have tumour profiling tests?
The National Institute for Health and Clinical Excellence (NICE) recommends tumour profiling tests for some people with breast cancer to help decide whether chemotherapy is needed after surgery. It is for people who have:
- oestrogen receptors in their cancer cells. This is oestrogen receptor positive breast cancer
- a small number of HER2 receptors. This is HER2 negative breast cancer
- no cancer cells in the
lymph nodes - an intermediate risk of the cancer coming back in another part of the body
Speak to your doctor if you want to find out more about tumour profiling tests. Some tests are not recommended by NICE and are not available on the NHS. These include:
- IHC4+C – as there is not enough evidence to show that it is reliable
- MammaPrint – because it is not cost effective
It’s also important to know that NICE only covers England and Wales. Your cancer specialist can tell you what tumour profiling tests are available if you live in Scotland or Northern Ireland.
What next?
You might want to read about the different types of treatments for breast cancer.
