Types and subtypes of breast cancer

We explain the types and subtypes of breast cancer and the language used to describe them. We also cover the different ‘stages’ and what it means if the breast cancer is invasive or non-invasive.

This information is important because each type and subtype may respond to different treatments.

Invasive or non-invasive?

All breast cancers are described as invasive or non-invasive.

Invasive breast cancers

When invasive breast cancer is diagnosed, it means the cancer cells:

• have spread outside of the ducts or lobules into surrounding breast tissue
• may or may not have spread into the lymph nodes in the breast or under the arm.

The two most common types of invasive breast cancer are:

• invasive ductal carcinoma (at least 80% of all diagnosed breast cancers)
• invasive lobular carcinoma (around 10% to 15%).

Less common and rare types include Paget’s disease, phyllodes tumours and inflammatory breast cancers.

Read more about invasive breast cancers.

Non-invasive breast cancers

When we describe breast cancers as ‘non-invasive’, the abnormal cells are still within the milk ducts or lobules in the breast. They have not grown into, or invaded, the normal breast tissue.

Non-invasive cancers are called ‘carcinoma in situ’ (‘in place’). They may also be referred to as ‘pre-cancers’ or ‘stage 0’.

Ductal carcinoma in situ or DCIS is the most common type of non-invasive breast cancer.

Lobular carcinoma in situ (LCIS) is considered a non-cancerous (‘benign’) breast change and not a breast cancer. 

If non-invasive breast cancers are not treated, they may spread into surrounding breast tissue. When this happens, it becomes invasive breast cancer.

Note: Some health professionals refer to both DCIS and LCIS as conditions or abnormal breast cell changes. Others refer to them both as non-invasive breast cancers.

Subtypes of breast cancer

All breast cancers – invasive and non-invasive – are classified by subtype and grade.

The subtype refers to how the cancer cells behave. It is important to help doctors choose treatments that are most likely to kill the cancer cells. It also gives them information about how the cancer may grow and develop (‘prognosis’). 

This information is part of your pathology report.

Hormone receptor-positive breast cancer

Hormone receptor positive breast cancers use female hormones (oestrogen and/or progesterone) to grow and reproduce. About 70% to 80% of breast cancers are hormone receptor positive.

HER2-positive breast cancer

Around 20% of breast cancers are HER2-positive. These tend to be faster-growing than HER2-negative breast cancer, but there are a number of very effective targeted treatments.

HER2-low breast cancer

HER2-low breast cancer is a new sub-category of breast cancer. Clinical trials show some drugs work really well on metastatic breast cancers that have lower amounts of the HER2 protein.

Triple negative breast cancer

Around 15 per cent of breast cancers are triple negative.

Triple negative breast cancer does not have any of the three receptors (oestrogen, progesterone and HER2) that cause breast cancers to grow.

Treatment such as radiation, surgery, chemotherapy and immunotherapy is generally recommended for these cancers.

Triple positive breast cancer

When breast cancer cells are tested, they may be both hormone receptor positive and HER2-positive. This is triple positive breast cancer.

How to identify the subtype of breast cancer

Usually, some cells or tissue will be taken out of the breast or lymph nodes with a biopsy. A pathologist tests the cells to identify which subtype of breast cancer it is. This test looks for biological markers (‘receptors’) such as oestrogen and progesterone and HER2 status.

People who develop metastatic breast cancer after early breast cancer may have a new biopsy. This will check whether the receptor results have changed. Sometimes doctors use the results from the previous cancer.

At your first diagnosis (early breast cancer or metastatic breast cancer), you’ll need a biopsy to confirm the diagnosis and to check the receptor status. 

The Breast Cancer Trials website has clear information about the types of breast cancer.

Research to identify more subtypes

Research is continuously increasing what we know about cancer cells and how they behave.

As scientists learn more about the chemical and genetic make-up of breast tumours, we expect them to identify more subtypes.

Therefore, treatment will become more and more specific to an individual cancer. Developing ‘personalised’ treatment is the main goal of current research.