What Is Metastatic Breast Cancer?

This article will provide you with the information needed to expand your knowledge of Metastatic Breast cancer, whether you are searching for yourself or somebody close to you. This article will focus on explaining the condition, what to expect, and what support is available. 

Metastatic Breast Cancer is when a cancer that was originally in your breast spreads to another part of the body. This kind of cancer may also be referred to as stage IV cancer.¹

Metastatic means that cancer cells from the primary tumour (the tumour that developed first) travel to and grow in another part of the body, causing another tumour to form (known as a secondary tumour). There can be more than one secondary tumour form in metastasis.²

Coming to terms with having this condition can often be a very scary experience. This article keeps this in mind and tries to tackle all the subjects it covers in an informative but sensitive manner. 

Below, we have more information to try and help ease your mind and to keep you well informed on the condition, so sit tight, grab something warm and comforting (a warm drink is always a nice idea!), and this article will be here waiting for you when you are ready.

Why is understanding metastatic breast cancer so important for your care?

Understanding your condition allows you to work actively with your healthcare providers so that you can be more involved and have more control over your care. This will allow you to make decisions which better suit you.³

Increasing your health literacy is important. (“Health literacy refers to the ability an individual has to access, understand, process and use information and services needed to make decisions about health” Link to definition). Low health literacy has been linked to depression and more difficulty when managing your own or family member's health.⁴

What is breast cancer?

Breast cancer, like other cancers, begins because of damage and mutations in the DNA.⁵

Breast cancer can originate from the lobules, which contain the glands that produce milk and form the lobes. 15 to 20 lobes make up one breast.^{6, 7}

Breast cancer can also begin in the ducts, which carry milk from the lobules to the opening in the nipple.^6,7

Breast cancers can spread and invade neighbouring tissue through a process called metastasis.⁸

Progression of breast cancer and what metastases are

This is a link to Cancer. A website run by the American Society of Clinical Oncology (ASCO) contains detailed explanations of the breast cancer-specific TNM (tumour, node, and metastases) staging and the staging groups. Link)

A combination of these TNM stages is grouped together to form stage groups. Metastatic breast cancer is Stage IV and includes any tumour that is metastatic (M1) and has any tumour size (T score) and any kind of involvement in the lymph nodes (N score). This is why you sometimes have metastatic breast cancer called stage IV breast cancer.⁹

Metastatic breast cancer can develop when cancer cells spread from the main (primary) tumour in the breast to another part of the body through the blood or the lymphatic system (The system parts of your immune system travel through)¹⁰ with both these systems stretching across the body which is why these cancers can spread so far. The cells then attach and grow into another new (secondary) tumour, making it possible for multiple secondary tumours to form from the same primary tumour.^2,9

Different types of metastatic breast cancer

HER2 positive

Around 15% of breast cancers rely on the HER2 gene, which stands for “Human Epidermal Growth Factor Receptor 2”, because of this, they are known as HER2-positive. These kinds of breast cancer are known as aggressive and fast-growing cancers. HER2-positive cancers can also have hormone receptors like oestrogen receptors or progesterone receptors.

During metastasis, HER2-positive cancers tend to spread to the bone, also spreading to the “visceral” (brain, Liver, lung.¹¹ areas are more common in HER2-positive cancers than in hormone receptor-positive cancers.^9,12

Hormone receptor-positive

Roughly 60% to 75% of breast cancers have receptors for Oestrogen or Progesterone; if the breast cancer has either of these, the breast cancer is known as hormone receptor-positive; if the breast cancer has neither of these, the breast cancer is known as hormone receptor-negative. Often, hormone receptor-positive breast cancers rely on estrogen or Progesterone to grow. Hormone receptor-positive breast cancers can appear at any age but are more common in women who have experienced menopause.^{9, 12}

Tripple-negative breast cancer (TNBC)

Triple-negative breast cancer, as the name suggests, is when there is negative ER, PR and HER2 (meaning that these are absent from the tumour) and makes up about 20% of all breast cancers and 15% of invasive breast cancers. TNBC is then split up into subgroups: Basal Like (BL1 and 2), claudin-low, ImmunoModulatory (IM), Luminal Androgen Receptor (LAR), and MESenchymal (MES). BL1 and 2 make up somewhere between 50% to 70% of cases, and claudin-low make up 20% to 30% of cases, making them the most common subgroups of TNBC. TNBC is aggressive, often can have early relapse, and is more likely to be diagnosed at an advanced stage. The course of the disease, along with the clinical outcome and which drugs are used in treatment, varies based on the subtype of the TNBC.^{9, 12}

Black women under 40 years old seem to be most at risk of Triple Negative Breast Cancer. The relatively famous BRCA1 gene mutation has been associated with TNBC.^{9, 12}

Symptoms

More specific symptoms

• Lump found on or around the breast⁵
• Pain in your bones⁵
• Pain in the abdomen⁵

Nonspecific symptoms

• Shortness of breath⁵
• Feeling unwell persistently⁵
• Nausea⁵
• Exhaustion⁵

Important: It is common for people to notice these changes in their bodies themselves, so if you are feeling any of these, it is important that you mention them to your doctor. It could be nothing, but it should be checked out.⁵

Diagnosis

You should first talk to your doctor if you think your cancer may be worsening or if you think it may have returned. This enables them to send you for specialist support at a hospital or breast cancer centre where they can investigate further. You may have already had some of these tests performed before if you had or were thought to have breast cancer in the past.⁵

How you may be assessed for breast cancer:

• Manual examination of the breast or surgery scar⁵
• Ultrasound⁵
• Biopsy (tissue sample)⁵

How you may be assessed for metastatic breast cancer:

• Chest x-ray⁵
• Bone scintigraphy (bone scan)⁵
• Ultrasound of the liver⁵

Usually, your’ clinician will check for metastases fter a diagnosis or re-diagnosis of breast cancer, and I f you have the general symptoms of breast cancer⁵

Treatment and management of the condition

As the cancer will have spread to another part of the body (due to the breast cancer being metastatic), the main objective of the treatment will be to maintain overall health and quality of life at as high a standard and for as long a time as is possible, this includes trying to slow down or stop any tumour growth.^{5, 13}

Which treatment is best suited to a person can vary based on the type of breast cancer that they have, with tailored therapies available for the different subtypes of breast cancer. However, breast cancer can still act very differently depending on where the cancer spreads to and how the cancer interacts with the different treatments, as people have very different responses to the same treatments.¹¹

Surgery

After metastases, surgical treatment is unlikely to remove all of the tumours, so another therapy will need to be used, possibly with other therapy such as radiotherapy.^{11, 14}

Chemotherapy

Used if the cancer is hormone receptor-negative. It is also used when the cancer has spread to the liver or lungs.¹³

Hormone therapy

A common treatment for breast cancer that has spread to other parts of the body (metastasised), it is particularly effective for hormone receptor-positive breast cancers.¹³

Radiotherapy

Typically used when the cancer has spread to the bones or the skin that is close to the breast.¹³

Targeted and immunotherapy

Relatively famous drugs such as trastuzumab (Herceptin), which is used in the treatment of HER2-positive breast cancer belong to this category.¹⁵

Symptom management

The following measures are put in place to regulate the symptoms associated with metastatic breast cancer:

• Pain management¹¹
• Measures to prevent chemotherapy-related nausea¹¹
• Dietary interventions¹¹
• Psychological support¹¹

The treatment and management of metastatic breast cancer is intense, with even the diagnosis being enough to make even the strongest among us feel worried or overwhelmed both physically and mentally.

Healthcare providers recognise this and so offer services both in and out of the hospital, with access to some services being available at your own home. Parts of the psychology team specialise in the wellbeing of those who are living with cancer, as various cancer information centres are available which can offer services like relaxation classes to help manage pain.⁵

Self-help groups are also an option and allow you to hear from others in similar positions to your own. You may feel that the solidarity and willingness of the members in the group to help one another is a big benefit to joining.⁵

Here is a link to access your regional cancer support organisation. Overseas cancer organisations | Coping with cancer | Cancer Research UK

Here is a link to questions you can ask your healthcare practitioner to help with understanding your diagnosis, treatment plan, and overall care: https://www.cancer.net/cancer-types/breast-cancer-metastatic/questions-ask-health-care-team