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What is metastatic breast cancer? ​​​​​​​ How do doctors make treatment decisions?SurgeryRadiotherapyChemotherapyHormone TherapyTargeted Therapy What matters most to you? Your doctor discussion guideYour questions answered
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What is metastatic breast 

What type of breast cancer do you have?

There are many different types of breast cancer. It’s not the same for everyone and the treatment you receive depends on a variety of factors such as:

  • Whereabouts the cancer is in the breast
  • Whether the cancer has spread to other areas of the breast
  • Whether the breast cancer has spread to other areas of the body

Different types of breast cancer

Ductal carcinoma ​​​​​​​ in situ (DCIS) is an example of non-invasive breast cancer where the cancer cells are contained within the ducts of the breast. In this form of cancer, the breast cancer cells have not spread to healthy breast tissue or other parts of the body.

Invasive breast cancer means the cancer has spread beyond certain parts of the breast (such as the ducts) and into healthy breast tissue. This means the cancer has the potential to spread to other parts of the body. If the cancer spreads, it is referred to as 'metastatic' or 'secondary'.

The most common forms of invasive breast cancer are:


Invasive ductal breast cancer (most common type)


The cancer cells started in the ducts of the breast and have now spread to the surrounding healthy tissue


Invasive lobular breast cancer (second most common type)


The cancer cells started in the ducts of the breast called lobules.

The cancer cells have now spread to surrounding healthy tissue

There are also other forms of breast cancer that are less common. These include inflammatory breast cancer  and Paget’s disease ​​​​​​​ of the breast.

What stage is your breast cancer?

Breast cancer can be split into different stages:

Stage of Breast Cancer Also known as Overview
Stage I Early or primary breast cancer Cancer is small and located in the breast. A few cancer cells may be found in the lymph nodes ​​​​​​​.
Stage II Early or primary breast cancer Cancer is a moderate size and located in the breast. Cancer can also be found in the lymph nodes.
Stage III Early or primary, or in some cases, locally advanced breast cancer. Cancer is larger and located in the breast and the lymph nodes.

If locally advanced, cancer has spread to the chest wall.
Stage IV Secondary, metastatic or advanced breast cancer Cancer has spread to other parts of the body such as the lungs, liver or bones.
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What are the symptoms of metastatic breast cancer?

After treatment for early breast cancer using surgery, radiotherapy and/or systemic therapy , it is possible for the cancer to return. The cells may break away from the tumour  and travel in the bloodstream or lymph system  to other parts of the body. This means the cancer can grow in another part of the body. This is known as metastatic breast cancer. Other names for this type of breast cancer include secondary, advanced or stage IV breast cancer. In some circumstances, the breast cancer is only detected when it has already progressed to become metastatic breast cancer.

The symptoms for metastatic breast cancer may be different from primary breast cancer. It is important to be aware of these symptoms and notify a doctor if you experience them.

General symptoms for metastatic breast cancer include:

  • Sudden weight loss for no reason
  • Loss of appetite
  • Feeling very tired all the time

Other symptoms depend on the part of the body the cancer has spread to. Examples of common places the cancer can spread to include the lungs, liver (visceral organs ​​​​​​​) or bones.

It is important to remember that the symptoms you may experience may not be caused by metastatic breast cancer. Additionally, there may be other symptoms you may experience that are not listed here. If you experience any symptoms, speak to your doctor.

What is my subtype?

Doctors will also test cancer cells to find the tumour’s ​​​​​​​ subtype. This helps them to decide which treatment or treatments will be most suitable.

The subtype of your breast cancer will depend on whether certain receptors are present on your cancer cells. These receptors are:

Hormone Receptors (HR)

Hormone receptors, including oestrogen  receptors (ER) and progesterone  receptors (PR) are present on the surface of cancer cells. Depending on the level of hormone receptors and how your tumour ​​​​​​​ responds to these hormones, your subtype will either be defined as HR- (low levels) or HR+ (higher levels).

Human Epidermal growth factor Receptor 2 (HER2)

HER2 ​​​​​​​ is a receptor found on the surface of cancer cells. Depending on the level of HER2 protein, your subtype will either be defined as HER2- (low levels of HER2) or HER2+(higher levels of HER2).

Your subtype will therefore be defined as one of the following:

  • HR+/HER2-
  • HR+/HER2+
  • HR-/HER2+
  • HR-/HER2-
commonly known as 'triple negative' due to the lack of ER, PR and HER2 ​​​​​​​The subtype of your cancer can help your doctor decide which treatment will work best for you.

How do Doctors make treatment decisions ?

The What’s Breast for Me? Campaign is funded by Pfizer Healthcare Ireland. Copyright © 2024 Pfizer Healthcare Ireland. All rights reserved. This site is intended for residents of the Republic of Ireland. The information provided on this site is intended for general information and education and is not intended to be a substitute for advice provided by a doctor or other qualified healthcare professional. All decisions regarding patient care must be made with a healthcare provider, considering the unique characteristics of the patients.


Date of preparation: January 2024