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What is breast cancer ?

Breast cancer is the most common cancer in women in Australia (apart from non-melanoma skin cancer) and the second most common cancer to cause death in women, after lung cancer.

Breast cancer is the abnormal growth of the cells lining the breast lobules or ducts. These cells grow uncontrollably and have the potential to spread to other parts of the body. Both men and women can develop breast cancer, although it is uncommon in men. Transwomen, non-binary people can also get breast cancer.

Transgender and gender-diverse people can also get breast cancer. A transgender woman taking medication to lower male hormones and boost female hormones may have an increased risk of developing breast cancer.

It is estimated that more than 20,600 people were diagnosed with breast cancer in 2023. The average age at diagnosis is 62 years old. 

Breast cancer is the second most commonly diagnosed cancer in Australia, and it is estimated that one in 1 in 8 females and 1 in 667 males will be diagnosed by the time they are 85.

Learn more about how Cancer Council funded researchers are developing new treatments for hard to treat breast cancers.

Breast cancer signs and symptoms

Some people have no symptoms and the cancer is found during a screening mammogram or a physical examination by a doctor.

If you do have symptoms, they could include:

  • new lumps or thickening in the breast, especially if in only one breast

  • nipple sores, change in shape of the nipple

  • nipple discharge or turning in

  • changes in the size or shape of the breast

  • skin of the breast dimpling

  • discomfort or swelling in the armpit

  • rash or red swollen breasts

  • ongoing pain that is not related to your menstrual cycle that remains after your period and occurs in only one breast.

Causes of breast cancer

Some factors that increase your risk of breast cancer include:

  • increasing age

  • family history

  • inheritance of mutations in the genes BRCA2, BRCA1  (more common with Ashkenazi Jewish heritage) and CHEK2

  • exposure to female hormones (natural and administered)

  • starting your period before the age of 12

  • a previous breast cancer diagnosis

  • a past history of certain non-cancerous breast conditions.

Lifestyle factors that can also slightly increase the risk of breast cancer in men and women include:

  • being overweight
  • not enough physical activity
  • drinking alcohol.

There is also an association with some benign breast disease and past exposure to radiation.

Diagnosis of breast cancer

Tests to diagnose breast cancer may include:

Physical examination

If you notice any breast changes or a mammogram shows something suspicious, your GP will perform a physical examination, checking both breast and the lymph nodes above your collar bone and above your arms. Your GP will also ask about your medical history and any family history of breast cancer.


A mammogram is a low-dose x-ray that can find changes that are too small to be felt during a physical examination. You should let staff know if you have breast implants before you have the mammogram.


If a mammogram picks up breast changes you may have an ultrasound. This is a painless scan using soundwaves to make a picture of your breast.


If breast cancer is suspected, a doctor removes some of the breast tissue for examination by a pathologist under a microscope.

Other scans

If cancer is detected in your breast, you may have additional scans to see if the cancer has spread to other parts of your body, such as a CT scan or MRI scan.

After a diagnosis of breast cancer 

After finding out you have breast cancer, you may feel shocked, upset, anxious or confused. These are normal responses. Talk about your treatment options with your doctor, family and friends. Seek as much information as you need. It is up to you how involved you want to be in decisions about your treatment.  

 Find out more information after a diagnosis of breast cancer:

Your guide to best breast cancer care

Your guide to best cancer care offers cancer specific guides describing the high-quality care you should expect at every stage of your treatment and beyond.

Treatment for breast cancer

Treatment depends on the extent of the cancer.


Staging involves assessing the size of the breast cancer and whether it has spread to the draining lymph nodes under the arm. A CT scan of the chest and liver and bone scan are done to check the sites to which breast cancers most commonly spread.


For localised breast cancer, the most extensive surgical option is to remove the breast and lymph nodes under the arm. When part of the breast is removed it is referred to as breast conserving surgery or a lumpectomy. Radiotherapy is generally recommended after breast conserving surgery.

When the whole breast is removed it is called a mastectomy.

Breast prostheses and reconstruction 

Before or after surgery you may think about how to restore your breast shape. You may consider a breast prosthesis or reconstruction. A breast prosthesis is a synthetic breast or part of a breast worn in a bra or under clothing to replace part or all of your breast. Breast reconstruction is an operation to make a new breast. Talk to your health care team about your options.


Chemotherapy may be used to help shrink the cancer before surgery, if the risk of cancer returning is high or if the cancer returns after surgery or radiation therapy. It may also be used if the cancer is HER2 positive or does not respond to hormone therapy.

Radiation therapy (radiotherapy)

Radiation therapy (radiotherapy) is recommended after breast-conserving surgery to help destroy any undetected cancer. It is also recommended if lymph nodes were removed from under the arm and there is a risk that the cancer will return to this area. Radiation therapy can sometimes be used after a mastectomy if there is a risk of the cancer returning to the chest area.

Hormone therapy

Hormone therapy uses drugs to reduce the levels of female hormones in the body. This helps to stop or slow the growth of hormone receptor positive cancer cells. The type of hormone therapy you have will depend on your age, the type of breast cancer and whether you have reached menopause.

Targeted therapy

Targeted therapy drugs attack specific targets inside cancer cells. The drugs that are currently available are only useful for HER2 positive breast cancer.

Palliative care

In some cases of breast cancer, your medical team may talk to you about palliative care. Palliative care aims to improve your quality of life by alleviating symptoms of cancer.

As well as slowing the spread of breast cancer, palliative treatment can relieve pain and help manage other symptoms. Treatment may include radiotherapy, chemotherapy or other drug therapies.

Managing side effects  

Treatment for breast cancer and even the cancer itself, can cause side effects. The types and severity of any side effects you may experience will depend on the type of treatment you have and may vary from person to person.   

Side effects will vary depending on the type of treatment you have but most are temporary and there are ways to reduce or prevent them.   

Outlined below are some of the side effects you may experience.   


When lymph nodes have been damaged or removed, lymph fluid may not be able to drain normally, causing a build up in the tissues of part of the body, such as an arm or breast. This swelling is called lymphoedema.  

Lymphoedema can occur during treatment or months or years after treatment. Look for swelling, heaviness or fullness in the fingers, wrist or whole arm, a feeling of tightness and aching in the affected area. Some people may also experience fever, redness or pain, caused by an infection called cellulitis. If you have any of these symptoms you should see your doctor as soon as possible as lymphoedema is easier to manage if it is diagnosed and treated early.  


Cording (auxillary web syndrome) can happen weeks or months after surgery and is caused by hardened lymph vessels. It feels like a tight cord running from your armpit down the inner arm and sometimes to the palm of your hand. You may feel and see raised cord-like structures across your arm and these may limit movement.  

Cording usually improved over a few months and gentle stretching exercises during the first weeks after surgery can help.  

Nerve pain 

Mastectomy or surgery to remove lymph nodes can cause nerve pain in the arm. Mastectomy can also cause nerve pain in the chest wall. It may feel like pins and needs but usually settles within a few weeks. If pain persists, talk you’re your doctor about ways to manage it.  

Some chemotherapy drugs can damage nerves in the hands and feet and this is called peripheral neuropathy. Peripheral neuropathy can cause pins and needles, numbness and, occasionally, pain. The symptoms are usually temporary but can be permanent. If you have any symptoms, let your health care team know so they can adjust your treatment. Your doctor will also be able to help you manage pain from permanent nerve damage.  

Changes to memory and thinking  

Some people diagnosed with breast cancer notice changes in how they remember information and the way they think. This is called cancer-related cognitive impairment. It is also referred to as “cancer fog” or “chemo brain”.  

While the precise cause is unknown, studies show that think and memory changes may be caused by the cancer itself, cancer treatments, medication given for surgery such as anaesthetic, emotions like depression and anxiety, and treatment side effects like insomnia, fatigue and hormone changes.  

For most people, issues with thinking and memory get better within the first year after finishing treatment but others might experience more long-term effects. Talk to your health care team about ways to cope with changes such as maintaining a healthy lifestyle or adjusting your daily routine.  

If you have severe or lasting changes to your thinking and memory, you can see a neuropsychologist or clinical psychologist for cognitive rehabilitation.  

Breast prosthesis 

breast prosthesis is a synthetic breast or part of a breast worn under clothing or in a bra to replace all or part of your breast. A breast prosthesis can be worn after breast-conserving surgery or a mastectomy. 

Most breast prostheses have the shape and feel of a natural breast. They may weight the same or be lighter. Breast prostheses can be attached directly to the skin or inserted into specially made pockets in bras, sleepwear and activewear. 

Hair loss 

Hair loss is one possible side effect caused by cancer treatments. Not all cancer treatments will cause hair loss – it is mostly associated with chemotherapy and radiation therapy. Treatments like targeted therapyhormone therapy and immunotherapy are more likely to cause hair thinning or slow growth of hair.  

If you lose your hair during cancer treatment, you may like to wear a wig, scarf, hat or turban while it is growing back. Some people are happy to leave their head bare. Some hospitals and cancer care units provide wigs for free or a small free.  

Menopause and changes to fertility 

Chemotherapy can cause your periods to stop for a time and may affect your ability to become pregnant. If your periods stop permanently (known as early menopause), you will not be able to conceive children naturally. Talk to your doctor before treatment begins if you think you would like to have children in the future.  

Symptoms of menopause can include, trouble sleeping, hot flushes, tiredness, mood swings, weight gain, and osteoporosis. Talk to your doctor about ways to relieve symptoms.  

You will not necessarily experience all these side effects and you may experience others that are not discussed here. It is important that you talk to your treatment team about any changes to your body during and after treatment.  

Treatment Team

Depending on your treatment, your treatment team may consist of a number of different health professionals, such as:
  • GP (General Practitioner) - looks after your general health and works with your specialists to coordinate treatment.
  • Radiologist- interprets diagnostic scans (including CT, MRI and PET scans).
  • Radiation oncologist - prescribes and coordinates radiation therapy treatment.
  • Medical oncologist - prescribes and coordinates the course of chemotherapy.
  • Breast care nurses- provide information and support to people affected by breast cancer during and after treatment.
  • Surgeon- surgically removes tumours and performs some biopsies.
  • Reconstructive (plastic) surgeon- performs any complex reconstructive surgery that restores or repairs the body's appearance and function.
  • Lymphoedema therapist- educates people about lymphoedema prevention and management, and provides treatment if lymphoedema occurs.
  • Other allied health professionals - such as social workers, pharmacists, and counsellors.

Screening for breast cancer

Women aged between 50 and 74 are invited to access free screening mammograms every two years via the BreastScreen Australia Program.

Women aged 40-49 and 75 and over are also eligible to receive free mammograms, however they do not receive an invitation to attend.

It is recommended that women with a strong family history of breast or ovarian cancer, aged between 40 and 49 or over 75 discuss options with their GP, or contact BreastScreen Australia on 13 20 50.

Preventing breast cancer

There is no proven method of preventing breast cancer, however the risk of breast cancer can be reduced by lowering alcohol consumption and maintaining a healthy weight.

Women who are at high risk because of a very strong family history may benefit from hormones such as tamoxifen, usually administered over five years. Bilateral prophylactic mastectomy can be considered in women at high risk of breast cancer due to gene mutations.

Prognosis for breast cancer

It is not possible for a doctor to predict the exact course of a disease, as it will depend on each person's individual circumstances. However, your doctor may give you a prognosis, the likely outcome of the disease, based on the type of breast cancer you have, the test results, the rate of tumour growth, as well as your age, fitness and medical history.

The most common types of breast cancer have a very good long-term prognosis, especially if the cancer is found early.


  • Understanding Breast Cancer, Cancer Council Australia  © 2020. Last medical review of source booklet: July 2020. 
  • Australian Institute of Health and Welfare. Cancer data in Australia [Internet]. Canberra: Australian Institute of Health and Welfare, 2023 [cited 2023 Sept 04]. Available from:

This information was last updated September 2023.