About breast cancer

About breast cancer

Breast cancer occurs when abnormal cells in the breast tissue multiply and form a tumour. In the majority of invasive breast cancers, the tumour begins in the lining of the milk ducts. If undetected, these cancer cells may also spread to other parts of the breast, the surrounding lymph nodes, and to other parts of the body.

Breast cancer is not a single disease. Researchers now think there may be up to 10 subtypes, with differences in how aggressive the cancer is, and how it responds to treatment. As more than 75% of all breast cancers occur in women aged 50 and over, due to Australia’s ageing population, the incidence of breast cancer is rising. However, significant advances in the early detection and treatment of breast cancer mean more patients are surviving breast cancer than ever before.

We're currently running a series of clinical trials covering various stages of breast cancer

  • Risks & Symptoms
  • Diagnosis
  • Treatment

Risks include:

  • Gender – being female is the biggest risk factor for breast cancer, although approximately 1% of new cases are in males
  • Age – more than 75% of all breast cancer occurs in women aged 50 and over. The average age of diagnosis is 68 years, with less than 10% of all cases occurring in women under 40
  • Family history – there is a higher risk of breast cancer in women with a family history, although inherited cancers account for less than 10% of all breast cancer cases. The BRCA1 and BRCA2 genes have been implicated in familial breast cancer and tests for these are available through genetic counselling services. However, there are many other inherited genes that could predispose to breast cancer that are not routinely tested for
  • Previous history of hormone-based breast disease; for example, benign cysts or fibroadenomas. This tends to only be a higher risk when aged over 50
  • Early commencement of menstruation or late menopause
  • Having your first child after the age of 30.


All women are encouraged to examine their breasts for lumps on a regular basis. While most breast lumps are not cancers, any new lump that does not go away should be examined by a physician, who may investigate further with ultrasounds, mammograms and/or biopsies. Women over 50 or those with a family history of breast cancer are encouraged to have a screening mammogram every two years.

This content is provided for informational purposes only. It is not a substitute for professional medical advice, diagnosis or treatment. If you have any concerns or questions about your health, please consult a suitably qualified healthcare professional.

Most breast lumps are not cancers; however, any new lump that does not go away after three to four weeks should be examined by a GP. Depending on the circumstances, a follow-up referral to a breast surgeon or a breast clinic for further tests may be appropriate. An ultrasound of the breast is simple and painless.

Mammograms are breast x-rays and involve the breast being compressed between two plates so that the radiographer can clearly see the tissue in question. A biopsy, if needed, is done under a local anaesthetic with a small needle similar to the type used in blood tests.

If you are over 50, or have a family history of breast cancer, it is recommended that you have a mammogram every two years. These are provided as a free health service. If you are under 50 it is still important to conduct an examination of your own breasts every month, ideally just after a period. If you notice anything unusual, consult your GP.

Treatment depends on the type of breast cancer and its stage and any previous diagnosis of breast cancer. The main treatments for breast cancer are surgery (removal of the lump, the breast, or the breast plus surrounding lymph node tissue), radiotherapy and systemic therapies, such as chemotherapy, anti-estrogen therapies and targeted therapies.

Approximately 70% of all breast cancers are sensitive to estrogen (ER positive) and/or progesterone (PR positive). These tumours have better outcomes, and can be treated with anti-estrogen therapies.

In about 20% of breast cancers, the cells make too much of a protein known as HER2. These cancers tend to be more aggressive and fast-growing, but can now be treated effectively with therapies targeting HER2.

Finally, approximately 15% of breast cancers are known as ‘triple negative’ because they are not ER positive, PR positive or HER2. This subtype tends to be the most aggressive, and currently, chemotherapy is the only standard treatment option. Most breast cancers associated with inherited mutations in the BRCA1 gene are triple negative.

In spite of these therapies, some patients will have a relapse of their cancer. In addition to standard therapies, patients may access new treatments through clinical trials.