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Breast cancer

13-minute read

Key facts

  • Breast cancer is the second most common cancer diagnosed in females, after skin cancer.
  • Risk factors for breast cancer include drinking alcohol, smoking, having a family history or genetic mutation and not being physically active.
  • Breast cancer screening aims to find breast cancers before you notice a lump.
  • Treatments for breast cancer include surgery, radiation therapy and different types of medicines including chemotherapy and hormone therapy.

What is breast cancer?

Breast cancer occurs when cells in the breast grow abnormally and in an uncontrolled way. This form a cancerous lump, known as a tumour. If left untreated, breast cancer may spread from breast tissue to other parts of the body, such as the bones, liver or lungs.

Breast cancer affects both males and females, although it is much less common in males.

There are some pre-cancerous breast conditions, also referred to as 'pre-invasive' or 'carcinoma in situ'. This is when there are abnormal cells inside the milk ducts or milk-producing lobules of the breast, but not into nearby tissue.

‘Invasive’ breast cancers grow within normal breast tissue and may spread to elsewhere in the body. The most common types are ductal carcinoma and lobular carcinoma. Other types include Paget’s disease, and inflammatory breast cancer.

Breast cancer is often defined by whether certain hormone receptors are found in the cancer. For example, hormone receptor positive breast cancer, HER-2 positive breast cancer or triple negative breast cancer (which tests negative for oestrogen, progesterone and HER-2).

Aside from skin cancer, breast cancer is the most common cancer in females. With early detection and treatment, 9 in 10 females with breast cancer survive at least 5 years. Many live much longer.

Illustration of the anatomy of the female breast.
Female breast anatomy.

What are the symptoms of breast cancer?

Symptoms of breast cancer can include:

  • a lump or area of thickened tissue in the breast (especially if only on one side)
  • a change in the size or shape of one or both breasts
  • a change in the shape or appearance of the nipple, such as crusting, sores, redness or inversion (where the nipple turns in instead of pointing out)
  • changes to the skin of the breasts, such as dimpling (looking like an orange peel), indents, rash or redness
  • discomfort or swelling in one armpit
  • pain in one breast that is not related to your menstrual cycle or continues after your period

Symptoms of breast cancer in males are similar to those that females experience.

If you have any unusual breast changes, such as the symptoms listed above, you should see your doctor to get them checked.

CHECK YOUR SYMPTOMS — Use the Symptom Checker and find out if you need to seek medical help.

What causes breast cancer?

While there is no specific cause for breast cancer, some lifestyle factors are linked with a higher risk of developing the condition:

  • drinking alcohol — the risk increases as you drink more alcohol
  • not doing enough physical activity
  • excessive weight — living with obesity is associated with an increased risk of breast cancer after menopause
  • smoking, particularly if you started as a teenager

Other factors that can’t be changed also impact your likelihood of getting breast cancer:

  • being female — 99% of breast cancers are in females
  • older age — the older you are, the more likely it is your cells become damaged and progress to cancer
  • family history — having multiple relatives on the same side with prostate, pancreatic, breast or ovarian cancer may increase your risk
  • gene mutations, especially BRCA1, BRCA2 — up to 1 in 10 breast cancers are due to having one a genetic mutations
  • having dense breast tissue
  • previous radiation exposure

What’s your risk?

Click here to learn about iPrevent — a breast cancer risk assessment tool to help you start a discussion with your GP about your risk.

When should I see my doctor?

See your doctor or healthcare professional if you notice symptoms of possible breast cancer, such as a lump, pain, itch, nipple discharge or dimpling or if you have any concerns about your breast cancer risk.

Your doctor or healthcare professional will assess you and work out if you need further tests. If required, they can refer you to a local service and provide necessary follow-up care.

FIND A HEALTH SERVICE — The Service Finder can help you find doctors, pharmacies, hospitals and other health services.

Can I be screened for breast cancer?

BreastScreen Australia offers a free screening program, because screening with a mammogram can diagnose a breast cancer earlier than if it is seen or felt.

  • If you’re aged between 50 and 74 years, you’ll be invited to have a free mammogram every 2 years. This is because nearly 4 in 5 breast cancers occur in females aged over 50 years.
  • If you’re aged between 40 and 49 years or over 75 years, you are also eligible but won’t be contacted about it.

Females under 40 years of age are usually not offered breast screening, because the density of their breast tissue makes it harder to detect cancers on mammograms. Most breast cancers occur in females over 50 years old.

Females younger than 50 years with a strong family history of breast or ovarian cancer may also benefit from breast screening.

How is breast cancer diagnosed?

Tests to confirm a breast cancer

To find the cause of a breast change, your doctor will typically use a 3-step process called the 'triple test', which includes:

  • taking your medical history and performing a clinical breast examination
  • imaging tests, such as a diagnostic mammogram or ultrasound
  • a biopsy, which involves taking a sample of tissue cells and looking at them under the microscope to check if there is cancer

The biopsy sample is taken from an area of the breast that is abnormal on the examination or imaging of the breast.

Staging and further tests

If breast cancer is confirmed, your doctor will referred you for more tests, such as a CT scan, blood tests, bone scans or a PET scan, to confirm the stage of your cancer.

Your healthcare team may use a 5-stage system:

  • Stage 0 (in situ) refers to pre-invasive breast conditions that’s only in the milk ducts or lobules of the breast
  • Stage I to IIB (early) refer to early breast cancer of a small size (5cm or less).
  • Stage IIB to Stage IIIC cancers (advanced, localised) have spread to nearby lymph nodes in the breastbone or armpit.
  • Stage IV cancer (advanced, metastatic) have spread to other parts of the body.

There may also be other tests performed on the biopsy sample. For example, your sample may be tested for hormone receptors (to see if your cancer cells have receptors for estrogen or progesterone), HER-2 (a protein that promotes cancer cell growth) or other genetic markers. These tests help you and your doctor determine the best treatment for your type of breast cancer.

ASK YOUR DOCTOR — Preparing for an appointment? Use the Question Builder for general tips on what to ask your GP or specialist.

How is breast cancer treated?

The treatment your health team will recommend depends on the specific type and stage of the breast cancer that you have.


This treatment involves removing localised cancer from the breast. A lumpectomy (‘breast conserving surgery’) involves removing the cancer and some healthy tissue but keeps as much of the breast as possible. A mastectomy involves removing the whole breast affected by cancer. During breast surgery, lymph nodes in the armpit are also often removed.

Radiation therapy

Radiation therapy (radiotherapy) is often used to destroy any breast cancer cells left following a lumpectomy. It is sometimes used after a mastectomy, if there is a risk of cancer recurring in the chest area.

You may need radiotherapy to your armpit if you don’t have lymph nodes removed with surgery.


Chemotherapy involves using anti-cancer drugs to kill the remaining cancer cells in the body. It may be used before or after surgery or radiation therapy, or together with other treatments.

Hormone therapy

Hormone therapy involves taking medicines that reduce or block your body’s oestrogen and progesterone levels. It is used to stop or slow hormone receptor positive cancer cells from coming back.

Targeted therapy

Targeted therapy uses medicines to specifically target cancer cells. Currently, they are mainly used for HER-2 positive breast cancers. Targeted therapy may be used before surgery.

PARP inhibitors

PARP inhibitors are a new type of medicine that is used if you have a BRCA mutation.

Palliative care

In some cases, especially if your cancer is advanced, your medical team will talk to you about palliative care. Palliative care aims to improve your quality of life by relieving your symptoms, rather than aiming to cure the cancer.

Who provides breast cancer treatment?

Your medical team will include many different health professionals. It may include a GP, a radiologist, an medical and radiation oncologist, a breast care nurse, a surgeon and allied health professionals such as counsellors and dietitians. Having a multi-disciplinary team means you receive the best care possible.

Sometimes, understanding the role of each health professional in your care team can be confusing. Ask your doctor if a cancer care coordinator is available. A cancer care coordinator is a health professional who coordinates your care, helps you communicate with all the health professionals involved in your treatment, and supports you and your family throughout your cancer experience.

Can breast cancer be prevented?

Unfortunately, there isn’t a way to prevent breast cancer completely. However, addressing any risk factors can help reduce your risk. Lifestyle choices such as maintaining a healthy diet, keeping physically active and lowering your alcohol consumption can help to reduce your risk of breast cancer.

If you are at high risk of developing breast cancer, there may be measures you can take to reduce your risk. These may include taking hormone therapy (such as tamoxifen) or having a pre-emptive mastectomy. You can discuss with your doctor whether these options are suitable for you.

Are there complications of breast cancer?

Possible complications from breast cancer and its treatment include the following:

  • Lymphoedema — in some cases, removing your lymph nodes may cause fluid to build up in your arm or breast causing swelling, discomfort and pain in the arm, shoulder and upper body.
  • Early menopause or menopausal symptoms — chemotherapy and hormone therapy, can cause menopause symptoms, such as hot flushes, joint pain, or a change in sex drive, to occur earlier than usual. Chemotherapy can damage your ovaries and stop them from making hormones permanently which results in menopause. Hormone medicines usually cause symptoms while you take them but don’t lead to permanent menopause. If your doctor wants your ovaries to stop making hormones, they may recommend removing them, leading to a permanent menopause.
  • Anxiety and depression — anxiety and depression are common among women with breast cancer, it is understandable to have these feelings. Your medical team can help you with treatments, so it’s important to let them know how you are feeling.

Living with breast cancer

Breast cancer can be challenging to deal with and to recover from. It’s important to give yourself time to come to terms with it, if you receive a breast cancer diagnosis and need treatment.

There are also many supports available. Read more on Living with breast cancer.

Resources and support

For more information and support, try these resources:

Learn more here about the development and quality assurance of healthdirect content.

Last reviewed: November 2023

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