What is breast cancer?

Breast cancer is the abnormal growth of cells lining the breast ducts or lobules. These abnormal cells grow and have the potential to spread to other parts of the body. Most breast cancers are found when they are invasive. This means the cancer has spread from the breast ducts or lobules into the surrounding breast tissue. Invasive breast cancer can be early, locally advanced or advanced (metastatic).

Types of breast cancer

Invasive breast cancers

The main types of invasive breast cancer are:

Non-invasive breast cancers
  • Ductal carcinoma in situ (DCIS) – Abnormal cells in the ducts of the breast.
  • Lobular cancer in situ (LCIS)  – Abnormal cells in the lobules of the breast. This is not cancer but increases the risk of developing cancer in either breast. However most women with this LCIS won’t develop breast cancer.

How common is breast cancer?

Apart from non-melanoma skin cancer, breast cancer is the most common cancer found in Australian women – it represents 28% of all cancers in women. Around 17,000 women are diagnosed with breast cancer each year, and one in eight women will be diagnosed with breast cancer by the age of 85.

Although it can occur at any age, it is more common in women over 40. Almost 70% of breast cancers are diagnosed in women aged 40-69, and about 25% in women aged 70 and over. In rare cases, women are diagnosed during pregnancy.

About 150 men are diagnosed with breast cancer in Australia each year and most of these men are over 50.

Risk factors

Many factors can increase your risk of breast cancer. But having risk factors does not mean that you will develop breast cancer.


Risk factors include:

  • Personal factors – older age; dense breast tissue as seen on a mammogram.
  • Lifestyle factors – being overweight or gaining weight after menopause; drinking alcohol every day; not being physically active.
  • Medical factors – using menopause hormone therapy (MHT) that contains both oestrogen and progesteron; taking the pill for a long time (small increase); taking diethylstiboestral (DES) during pregnancy; having radiation therapy to the chest for Hodgkin lymphoma; having atypical ductal hyperplasia or proliferative disease without atypia; previous diagnosis of LCIS or DCIS.
  • Reproductive factors – starting first period younger than 12; being older than 30 at the birth of first child; not giving birth; not having breastfed; going through menopause after 55.
  • Family history factors – a family history of breast cancer and/or a particular type of ovarian cancer. in first-degree relatives (e.g. mother, sister) on the same side of the family, especially if diagnosed at a young age.

Risk factors include:

  • Personal factors – older age.
  • Medical factors – a rare genetic syndrome called Klinefelter syndrome – males with this syndrome have three sex chromosomes (XXY) instead of the usual two (XY).
  • Family history factors – a family history, with several first-degree relatives (male or female) who have had BRCA2 breast cancer; a relative diagnosed with breast cancer under the age of 40; or several relatives with ovarian cancer or colon cancer.
  • Inheriting a mutation in the BRCA1 or BRCA2 genes.


Some people have no symptoms and the cancer is found during a screening mammogram (a low-dose x-ray of the breast) or physical examination by a doctor.

If you do have symptoms, they could include:

  • A lump, lumpiness or thickening, especially if it is only in one breast.
  • Changes to the nipple – such as a change in shape – crusting, a sore or an ulcer, redness, unusual discharge, or a nipple that turns in (inverted) when it used to stick out.
  • Changes to the skin of the breast, such as dimpling or indentation, a rash, a scaly appearance, unusual redness or other colour changes.
  • Changes in the size or shape of the breast.
  • Swelling or discomfort in the armpit.
  • Ongoing, unusual, pain that is not related to your normal menstrual cycle, remains after your period and occurs in one breast only.

Most breast changes aren’t caused by cancer. However, if you have any symptoms, have them checked by your doctor without delay.


If you have symptoms of breast cancer, your GP will take a full medical history, which will include your family history. They will also perform a physical examination, checking both your breasts as well as lymph nodes under your arms and above your collarbones.

To find out if your breast change has been caused by cancer, your GP may arrange some tests, such as a mammogram and biopsy. They may also refer you to a specialist for these and other tests.

  • Physical examination – your GP will feel your breasts and the lymph nodes under your arms.
  • Mammogram – is a low-dose x-ray of the breast tissue. This x-ray can check any lumps or other changes found during a physical examination. It can also find changes that are too small to be felt during a physical examination.
  • Ultrasound.
  • MRI scan.
  • Biopsy – a small amount of sample cells or tissue is removed from your breast. A specialist doctor called a pathologist examines the sample and checks it for cancer under a microsope.

Other tests include:

  • Bone scan – may be done to see if the breast cancer has spread to your bones.
  • Blood test – to check your general health and also test your bone and liver function for signs of cancer.
  • CT scan.
  • Chest x-ray – your doctor may take an x-ray of your chest to check your lungs for signs of cancer.

Some tests may be repeated during or after treatment to check how well the treatment is working. Waiting for the test results can be a stressful time. It may help to talk to a friend or family member, a healthcare professional, or call Cancer Council on 13 11 20.


Treatment for early or locally advanced breast cancer varies from person to person. The most suitable treatment for you will depend on your test results, where the cancer is in the breast, the cancer’s stage and grade, and whether the cancer is hormone receptor and/or HER2 positive or triple negative. Your doctor will also consider your age and general health, and what you want.

Treatment may include surgery, radiation therapy, chemotherapy, hormone therapy and targeted therapies.

Your doctors will consider the following factors to recommend the best treatment for you:

  • Your test results
  • Where the cancer is in the breast
  • The cancer’s stage and grade
  • Whether the cancer is hormone receptor or HER2 positive or triple negative.
  • Your age and general health
  • Your preferences.

For more information on the treatment of breast cancer please see our Understanding Breast Cancer booklet.


Prognosis means the expected outcome of a disease. You may wish to discuss your prognosis and treatment options with your doctor, but it is not possible for any doctor to predict the exact course of the disease.

Survival rates for people with breast cancer have increased significantly over time due to better tests and scans, earlier detection, and improvements in treatment methods. Most people with early or locally advanced breast cancer can be treated successfully.

Support for Queenslanders

Whether you have been diagnosed with breast cancer, or have a family member or friend who is affected by cancer, there are times when you may need support. Our professional services and support programs are here to help you.

Find out more about:

You don’t have to face cancer alone – we’re here to help.


For more information about Breast cancer, please see these resources

If you are a patient, family or friend and would like to order a copy of either the Understanding Breast Cancer or Understanding Breast Prostheses and Reconstruction booklets, please call Cancer Council 13 11 20