METASTATIC BREAST CANCER

Metastatic breast cancer, also known as advanced, secondary or stage 4 breast cancer, occurs when breast cancer spreads beyond the breast and local lymph nodes to other parts of the body, such as the bones, liver, lungs or brain.

While metastatic breast cancer is not currently curable, advances in treatment mean many people are living longer and maintaining a good quality of life. Treatment continues to evolve through advances in personalised medicine, targeted therapies and clinical trials, helping doctors tailor care to each person’s breast cancer. 

Metastatic breast cancer is treatable. Advances in treatment and research are helping many people live longer while maintaining quality of life. 

How Does Breast Cancer Metastasise? 

Metastatic breast cancer occurs when cancer cells break away from the cancer in the breast and travel through the bloodstream or lymphatic system and form a new cancer growth in other parts of the body. 

If breast cancer has spread and metastasised, it is still considered breast cancer and will be treated as such. This is because the cells which have spread are breast cancer cells.  

For example, if breast cancer has spread to the liver, the metastatic tumour in the liver is made up of breast cancer cells, not liver cells. 

What Are the Symptoms of Metastatic Breast Cancer? 

Symptoms of metastatic breast cancer vary depending on where the cancer has spread. The most common sites are the bones, liver, lungs and brain, although breast cancer can spread to other parts of the body. Some people experience symptoms, while others may have few or no symptoms when metastatic breast cancer is first diagnosed. 

Symptoms may include: 

• Bone metastasis: If breast cancer has spread to the bones, the most common symptom is a new pain or ache in the bone. Breast cancer can spread to any bone but is most commonly found in the ribs, spine, pelvis, and upper arms or legs. 
• Brain metastasis: If breast cancer has spread to the brain, you may have headaches, nausea, vomiting, vision or speech changes or memory problems. In some rare cases, symptoms can include seizures, confusion, or a change in personality. 
• Liver metastasis: If breast cancer has spread to the liver, symptoms may include weight loss, tiredness, and discomfort on the right side of the abdomen where the liver is located. Other less common symptoms include nausea, loss of appetite, jaundice and swelling of the abdomen. 
• Lung metastasis: Most commonly, the first symptom that breast cancer has spread to the lungs is a shortness of breath or a dry cough. Other less common symptoms include chest pain or a feeling of heaviness in the chest. However, it is common for breast cancer which has spread to the lung or lungs to present with no symptoms. 

Many of these symptoms can also be caused by conditions other than metastatic breast cancer. If you notice any new, persistent or worsening symptoms, speak with your doctor or treatment team so they can determine the cause and recommend any appropriate tests or treatment. 

How is Metastatic Breast Cancer Diagnosed? 

If your doctor suspects your breast cancer has spread (metastasised), they will recommend tests based on where they believe the cancer may have spread. These tests help confirm the diagnosis and guide treatment decisions. 

• Bone metastases: Blood tests, an X-ray, CT scan, MRI, bone scan, or PET scan may be used to determine whether breast cancer has spread to the bones.  
• Lung metastases: Tests may include examination of mucus (sputum) under a microscope, a chest CT, bronchoscopy, a lung needle biopsy or, in some cases, surgery.  
• Brain metastases: A CT or MRI scan of the brain, often performed with contrast, is commonly used to detect cancer in the brain. In rare cases, an operation may also be required.  
• Liver metastases: Liver function blood tests, an ultrasound, CT scan, MRI, PET scan and/or a biopsy may be used to assess whether breast cancer has spread to the liver. 

Your doctor will recommend blood tests, imaging tests and, in some cases a biopsy depending on your symptoms and where the cancer is suspected to have spread. 

How Is Metastatic Breast Cancer Treated? 

Every case of metastatic breast cancer is different, so treatment is tailored to each person’s individual circumstances. Although the cancer has spread to another part of the body, such as the bones, liver, lungs or brain, it is still treated as breast cancer because the cancer cells originated in the breast. 

The aim of treatment is to control the growth and spread of the cancer, relieve symptoms, maintain quality of life and help people live well for as long as possible. Your treatment plan will depend on several factors, including the type of breast cancer, where it has spread, previous treatments, your overall health and your treatment goals. 

Treatment options for metastatic breast cancer continue to evolve and may include endocrine (hormone) therapy, chemotherapy, targeted therapies, HER2-targeted therapies, immunotherapy, radiotherapy and, in selected situations, surgery.

Clinical trials also play an important role by investigating new treatments that may improve outcomes and expand future treatment options for people living with metastatic breast cancer. 

How Treatment for Metastatic Breast Cancer is Becoming More Personalised 

Treatment for metastatic breast cancer is becoming increasingly personalised. Rather than using the same treatment approach for every person, doctors now consider the biology of an individual’s cancer, including hormone receptor status, HER2 status and other tumour characteristics. 

For many people with hormone receptor-positive, HER2-negative metastatic breast cancer, treatment often begins with endocrine therapy combined with targeted medicines. People with HER2-positive metastatic breast cancer commonly receive HER2-targeted therapies with chemotherapy, while treatment options for triple-negative breast cancer continue to expand through ongoing research. 

Researchers are also exploring how tumour biomarkers, tumour testing and blood-based monitoring may help identify the most appropriate treatments for individual patients. These advances are helping move metastatic breast cancer care towards increasingly personalised treatment. 

Why Is Metastatic Breast Cancer Difficult to Treat?

Metastatic breast cancer can be more challenging to treat than early breast cancer because the cancer has spread beyond the breast to other parts of the body. As the disease changes over time, cancer cells may also become less responsive to treatments that were previously effective. 

Treatment decisions are influenced by several factors, including the breast cancer subtype, where the cancer has spread, previous treatments, and how the cancer is responding to therapy. Surgery is not commonly used to treat metastatic breast cancer because the disease affects more than one area of the body, although it may be recommended in selected situations. 

Researchers continue to investigate why breast cancer spreads and how it changes over time. This research is leading to new targeted therapies, more personalised treatment approaches and clinical trials that aim to improve outcomes for people living with metastatic breast cancer.  

Types of Metastatic Breast Cancer 

Although metastatic breast cancer has spread beyond the breast to other parts of the body, it is still classified according to the type (or subtype) of breast cancer it started as. The subtype of breast cancer helps doctors decide which treatments are likely to be most effective. 

The main subtypes of breast cancer are: 

• Hormone receptor-positive (HR-positive), HER2-negative (Luminal A): The most common subtype, which is typically treated with endocrine (hormone) therapy and targeted medicines.  
• Hormone receptor-positive (HR-positive), HER2-positive or high-grade disease (Luminal B): May be treated with a combination of hormone therapy, HER2-targeted therapies and other systemic treatments, depending on the characteristics of the cancer.  
• HER2-positive breast cancer: Treated using HER2-targeted therapies, often in combination with chemotherapy or other medicines.  
• Triple-negative breast cancer (TNBC): Does not express hormone receptors or HER2. Treatment may include chemotherapy, immunotherapy or other targeted therapies, depending on the individual cancer. 

In addition to the breast cancer subtype, your treatment team will also consider where the breast cancer has spread, previous treatments you have received, your overall health and your personal treatment goals when developing a treatment plan. 

How Common is Metastatic Breast Cancer? 

Metastatic breast cancer accounts for only a small proportion of new breast cancer cases. It is estimated that around 5% of all breast cancers diagnosed each year are metastatic at the time of diagnosis. The Australian Institute of Health and Welfare also estimates that approximately 21,000 Australians are currently living with metastatic breast cancer. 

Most people living with metastatic breast cancer were initially diagnosed with early-stage breast cancer before the disease spread to other parts of the body. However, for a small proportion of people, metastatic breast cancer is their first breast cancer diagnosis. 

What is the Metastatic Breast Cancer Survival Rate? 

Breast cancer survival is measured in 5-year relative survival. This measures the percentage of people diagnosed with breast cancer who are still alive five years after their initial diagnosis compared to people of the same age and sex who don’t have breast cancer. This is considered the most accurate measure of cancer survival as it adjusts for deaths from other causes. 

According to the latest official data from the Australian Institute of Health and Welfare in 2011, the five-year relative survival for those diagnosed with stage 4 breast cancer is 32%. The survival rates in New Zealand are similar. It is hard to know how this rate has changed since 2011, as there have been both an increase in the number of people diagnosed with breast cancer, as well as numerous treatment advances helping people live longer in this time. 

However, these statistics can’t predict your individual breast cancer prognosis. Breast cancer survival differs, and there are many factors that can influence this such as the subtype of breast cancer you have, where the breast cancer has spread in the body, your response to treatment, medical history, overall health and age. You should discuss your personal situation with your doctor and/or treatment team. 

Survival outcomes continue to improve as treatments become more personalised and new therapies become available through research and clinical trials. 

Is Metastatic Breast Cancer Curable? 

Currently there is no cure for metastatic breast cancer. However, new and better treatment options mean that breast cancer can remain under control for longer, sometimes for years at time. 

Those diagnosed with metastatic breast cancer will need to undergo treatment for the rest of their lives. If one treatment ceases to be effective in keeping the cancer under control, another treatment regime may be suggested. These treatments are generally given for as long as they are providing a benefit to the patient. The goal is to maintain the best quality of life achievable, and to prolong life if possible. 

Although metastatic breast cancer cannot currently be cured, advances in treatment mean many people are living longer than ever before. The aim of treatment is to control the breast cancer, relieve symptoms, maintain quality of life and help people live well for as long as possible. 

Breast Cancer Trials Research 

Breast Cancer Trials continues to support research aimed at improving treatment options for people living with metastatic breast cancer. 

Recent studies such as CAPTURE and FINER are helping researchers better understand how treatment can be tailored to an individual’s cancer. 

The CAPTURE trial explored biomarker-guided treatment approaches for people with metastatic HR-positive breast cancer, while the FINER trial investigated new targeted treatment strategies following standard endocrine therapy in the same patient group. 

Every Breast Cancer Trials study contributes valuable knowledge that helps improve future treatment decisions and supports the development of more personalised care for people living with metastatic breast cancer. Learn more about how Breast Cancer Trials research has improved breast cancer treatment through our achievements. 

Last updated: July 2026 
Clinical review: Dr Sarah Zardawi 

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