Subtypes of metastatic breast cancer

Breast cancer – whether metastatic or early breast cancer – has several subtypes. It’s important to know which subtype you have because this guides decisions around the best treatment.

The different subtypes of breast cancer that guide treatment are:

• hormone receptor positive or 'HR+'
• HER2-positive or 'HER2+'
• triple negative (not HR+ and not HER2+) 

In future, we expect to see more subtypes as scientists discover more about breast cancer cells and genes.

How the subtype is identified

Usually, you will have a biopsy of the metastases. This tissue is tested to identify the biological markers such as:

• oestrogen hormones
• progesterone hormones
• HER2 status.

The pathology report will show which subtype the breast cancer is. We have a factsheet to help you understand your pathology report.

If you previously had an early breast cancer, you probably had this test done at the time. When metastatic breast cancer is diagnosed, another biopsy will show whether the receptor results have changed. This happens in about 10% of cases.

Where a biopsy is not possible, often because of the location of the metastases, doctors will refer to the results from the original breast cancer.

If metastatic breast cancer is your first diagnosis (‘de novo metastatic breast cancer), you’ll need a biopsy to:

• confirm the diagnosis
• check for biological markers.

This tissue may be taken from the breast and from 1 of the sites of metastases.

Hormone receptor positive subtype

Around 70% of metastatic breast cancers are hormone receptor positive. 10% of these may also be HER2-positive.
In most cases, treatment for hormone receptor positive metastatic breast cancer starts with hormone-blocking therapy. This is given in the form of oral tablets.
Find out about:

• Hormone receptor positive breast cancers
• Treatment for hormone receptor positive metastatic breast cancer

HER2-positive subtype

Around 20% of metastatic breast cancers are HER2-positive. Around half of these cancers are also hormone receptor positive.

Treatments that block the HER2 receptors prevent this growth stimulation, controlling the cancer.

Find out about:

• Treatment for HER2-positive metastatic breast cancer

Triple negative metastatic breast cancer

Around 15-20% of metastatic breast cancers are triple negative. In this subtype, the cancer cells do not have any oestrogen, progesterone or HER2 receptors on the surface. 
The main treatment for triple negative breast cancer is chemotherapy.

Find out about:

• Triple negative metastatic breast cancer
• Treatment for triple negative metastatic breast cancer

Talking to your treating team

The pathology of your breast cancer is quite complex.

You probably won’t understand all the treatment options that may be available when you are first diagnosed. Doctors know that. We encourage you to keep asking questions until you understand the type of breast cancer you have, and why they recommend the treatments they suggest.

Over time you will have a better understanding of your subtype of metastatic breast cancer and its treatment.