Breast cancer

Breast cancer is where the cells in your breast begin to grow abnormally and rapidly, resulting in cancerous tumours, known as malignant tumours. Breast cancer can start in the lining of the lobules (milk-producing glands) or breast ducts and may spread into the surrounding tissues or distant organs.

Though breast cancer is typically combined under one category, the reality is that the complexities surrounding this disease include different stages, grades, types, tumour biology and subtypes and require a variety of treatment options, patient support, and ongoing care. Approximately 5 - 10% of breast cancers are due to a gene mutation inherited from either the father or mother and at times, the presence of a gene mutation can impact your cancer treatment. Early detection and reducing your risk can lead to the best possible outcome. Make sure you incorporate regular self-breast checks into your self-care routine and see your general practitioner (GP) immediately if you see or feel any unusual changes in your breasts. If you have a gene mutation which puts you at high risk of developing breast cancer, it is best to be part of a high-risk breast screening program to manage your risk.

How common is breast cancer?

Most people do not develop breast cancer. 

There are three major risk categories for breast cancer: low, moderate and high risk.

Low-Risk – Also referred to as ‘general population risk’, most people fall into this category and will not develop breast cancer in their lifetime. About 1 in 7 women and 1 in 542 men will develop breast cancer. The majority of breast cancers occur in women after age 50.

Moderate-Risk – In this category, the risk of breast cancer up to age 75 is between 1 in 8 and 1 in 4, although most people in this category will not develop breast cancer. This risk is 1.5 to 3 times the population average. 

High-Risk – Less than 1% of the population have a high risk of breast cancer. The risk of breast cancer up to age 75 is between 1 in 4 and 1 in 2. The individual risk may be higher or lower than this if genetic test results are known. 

For more information about breast cancer risk due to an inherited gene mutation read more here.

What are the common symptoms of breast cancer?

Breast cancer symptoms can vary for everyone, and some cancer may not have any obvious signs. 

The most common symptoms of breast cancer are:

Lump or thickening in the breast or underarm area – is often the first symptom of breast cancer. It may feel like a hard or firm area of the breast. It is often painless

Changes in the breast size or shape – may include swelling, skin irritation or redness that lasts a while despite possible use of antibiotics

Nipple discharge – may be clear or blood-stained fluid that leaks from one or both nipples generally spontaneously (without pressing the nipple) and comes from a single nipple duct

Inverted nipple – when the nipple may turn inward instead of sticking out. This can be normal, however, any recent nipple inversion should be further investigated by your GP

Changes in the breast’s skin texture – may include dimpling, puckering or a rash on the nipple or surrounding breast area and may resemble the same texture as an orange peel. This is uncommon and usually presents with more advanced changes within the breast.

Swelling in all or part of the breast – may occur even if there is no distinct lump.

Learn more about self-breast checks and breast screening.

What are the different types of breast cancer?

Breast cancer can be classified into different types and subtypes based on the characteristics of the cancer cells and how they look under a microscope.

Ductal carcinoma In Situ (DCIS) – Non-invasive; starts in the cells that line the breast milk ducts. This type is an early form of breast cancer and is highly treatable. However, if it is untreated or left undetected, it may become a more invasive form of breast cancer – 

Invasive ductal carcinoma (IDC) – A common breast cancer that starts in the milk ducts and spreads to other parts of healthy breast tissue

Lobular carcinoma (LCIS) – Occurs in the lobules (the glands that produce milk) and does not spread into surrounding breast tissue. This type does not always need treatment and rarely becomes invasive

Invasive Lobular carcinoma (ILC) – The second most common type of breast cancer begins in the lobules. This type can sometimes be difficult to detect early with a mammogram

Inflammatory breast cancer – A rare and aggressive type of breast cancer that may not present with a noticeable lump but can cause swelling and redness in the breast due to the cancer cells spreading into the skin and lymphatics of the breast. Symptoms of this type may be similar to mastitis: skin redness and swelling, thickening of breast tissue, fever, and breast tenderness. These symptoms generally persist despite the use of oral antibiotics to treat a possible breast infection/mastitis.

Metastatic Breast Cancer (MBC) – This type of breast cancer is also categorised as Stage IV and has spread to other body parts, such as the lungs, liver, brain, or bones. Metastases can happen when:

• Cancer cells invade into nearby healthy lymph or blood vessels
• Cancer cells can migrate to a distant area where it gets lodged and invade the surrounding healthy tissue. There is a new (smaller) tumour growth at a distant site.

Paget's disease of the breast or nipple (mammary Paget's disease) – Paget’s disease is a rare type of cancer that affects the skin around the nipple and the areola, causing redness, scaling, and discharge from the nipple. These symptoms may initially be misdiagnosed with other infections or other skin conditions. This tends to present in older women.

What are the subtypes of breast cancer?

Subtypes are based on the presence of specific proteins (biomarkers), and genes found in the tumour biology. Knowing this information, can help work out which treatments might be best suited for a particular cancer. There are three main subtypes of breast cancer:

Hormone receptor-positive (HR+) – This breast cancer subtype is fuelled by hormones such as estrogen and progesterone. HR+ breast cancer is often treated with hormonal therapy to block the effects of these hormones on the cancer cells. Breast cancers with these hormone receptors bind to estrogen and/or progesterone which facilitate the proliferation of the cancer cells.

Estrogen positive (ER+) and progesterone positive (PR+) – ER+ breast cancers make up about 80% of all breast cancers and have estrogen receptors on the surface of the cancer cells that can attach to the hormone estrogen. PR+ breast cancers have progesterone receptors on the surface of the cancer cells that can attach to the hormone progesterone. Sometimes, breast cancer cells can have estrogen and progesterone receptors on their surface, referred to as ER+/PR+. Both hormones play a vital role in developing and regulating the female reproductive system, helping maintain bone density, and affecting the skin, brain, and other organs.

The strength of hormone receptor positivity, meaning the number of estrogen or progesterone receptors on the surface of cancer cells, can vary between different breast cancers. All positive results – for either estrogen or progesterone receptors – will be classed as HR+ breast cancers and tend to be more responsive to hormonal therapy, whereas breast cancers that are hormone-receptor-negative with an Allred score of 0 will have little to no effect from hormonal therapy.

The strength of hormone receptor positivity can also affect the prognosis and treatment approach, which is why it is important for your doctor to test for both hormone receptors after your biopsy to get the most accurate diagnosis and treatment plan.

There are two types of hormone receptor positive breast cancers. Luminal A and Luminal B subtypes.

• Luminal A subtype – These are ER positive breast cancers that are low grade, slow growing and generally strongly ER and PR receptor positive. These cancers are not very aggressive and carry a good prognosis with complete treatment including endocrine treatment (hormone blocking drugs).
• Luminal B subtype – These are ER positive breast cancers that can be high grade, can grow more rapidly and are generally PR receptor weakly positive or negative. These cancers are often treated with chemotherapy and endocrine treatment.

HER2-positive breast cancers – These cancers test positive for a protein called human epidermal growth factor receptor 2 (HER2). This protein promotes the growth of cancer cells. HER2-positive breast cancers tend to be more aggressive than other types of breast cancer. With treatments including chemotherapy and targeted therapy that now specifically target HER2, the prognosis is good. HER2-positive breast cancers can be triple positive where ER and PR receptors are also positive in which case endocrine treatment (hormone blocking drugs) are often used.

Triple-negative breast cancer (TNBC) – TNBCs are breast cancers that are ER, PR and HER2 negative. They can be aggressive with sometimes a higher chance of recurrence after initial treatment. They can be fast-growing and therefore often first diagnosed when it has reached the later stages.

This subtype is characterised by the absence of the three main proteins that drive most types of breast cancer (HER2, estrogen receptors, and progesterone receptors). Triple-negative breast cancers do not respond to hormonal or targeted therapies. They are often treated with chemotherapy. Younger women with this subtype may have a genetic predisposition (that is, they may have a gene mutation such as BRCA) for their cancer but not always.

With many ongoing breast cancer trials and new drugs available, TNBCs are now also being treated effectively with a combination of chemotherapy and other systemic drugs.

What are the stages of breast cancer?

Because of the complex nature of breast cancer, the severity and progression are categorised by stages and grades to help make a more accurate diagnosis and determine the most effective treatment plan. It is important to note that different stages and grades of breast cancer can affect treatment options and prognosis, but early detection and treatment can improve outcomes.

Your doctor will use the TNM system to determine your staging:

T - relates to the primary tumour, its size, and whether it has spread to nearby tissue
N - identifies if the cancer is in the lymph nodes
M - explains if the cancer has spread beyond the breast into other organs of the body

The different stages specify the size of tumours and if cancer cells have spread to other areas of your body.

Early breast cancer (also described as localised)

• Stage 0: Non-invasive breast cancer, where the abnormal cells are contained within the ducts or lobules (such as ductal carcinoma in situ)
• Stage I: Invasive; the cancer is small, around 2cm or less, and is confined to the breast.
• Stage II (may be divided into IIA or IIB): Invasive; the tumour is between 2-5cm and has likely spread to the nearby lymph nodes under the armpit.

Locally advanced breast cancer (also described as regional)

• Stage III (may be divided into IIIA, IIIB, IIIC): In this stage, cancer may be larger than 5cm and has spread to regional lymph nodes, or into the chest wall including the underlying muscle or overlying skin.

Metastatic breast cancer

• Stage IV: In this stage, the cancer has spread to distant organs, such as the bones, brain or lungs.

What are the grades of breast cancer?

The pathologist will use the Nottingham Grading system to describe the abnormality of the tumour cells and discover how quickly the tumour cells are growing. The grading system looks at:

1. The size and shape of the nucleus (the “brain” of the cell)
2. The organisation of the cells and if they look like they are working together.
3. How many of the cells are dividing and growing.

Based upon the above criteria. The cancer is then graded from 1-3:

• Grade 1 (low): The cancer cells are growing slowly and do not look very disorganised compared to normal cells.
• Grade 2 (intermediate): The cancer cells are abnormal and look a bit more disorganised, but not as much as Grade 3 cells and grow at a moderate rate.
• Grade 3 (high): The cancer cells are highly abnormal, look very disorganised and growing rapidly.

What are my treatment options?

A patient will be recommended treatment options for breast cancer based on many factors including the stage of cancer, the molecular subtype of cancer, overall health and personal preferences. 

For more information about your treatment plan, team and options click here

Learn more about the different surgery options available. 

Learn more about ‘Tumour Testing’ and if this should be considered after your diagnosis 

I’ve had breast cancer. What are my chances of recurrence?

The road to good health following breast cancer is not always easy and is often difficult to navigate. Unfortunately the risk of recurrence for any person who has had a breast cancer diagnosis is never going to be zero. The risk of breast cancer recurrence is at its highest within the first two years after an initial diagnosis. As time passes, the risk of recurrence steadily decreases. For those who have had five-years cancer free, there is a relatively low risk of recurrence at allThe risk of recurrence of breast cancer after five years, also known as late-stage recurrence, is incredibly low. It is generally related to age, the stage of diagnosis, hormone receptor status, genetic information and lymph node involvement. 

When a late recurrence of breast cancer is found, your healthcare team will evaluate and categorise all the details for you to help you plan your treatment pathway. While breast cancer recurrences tend to be the same type and have the same hormone receptor status, for some people, it can change. This critical information will help to determine your treatment plan and give you the best chance for a successful outcome.For more information on cancer survivorship, see our Resources Centre.

For more information on breast cancer please visit Breast Cancer Network Australia.