Breast cancer

Wednesday 28 February, 2007


This information has been reviewed by:
Dr Meron Pitcher (Chair VCOG Breast Cancer Committee), Surgeon, Western Hospital

Breast cancer bookletUse the links above and text below to learn more about breast cancer or download a pdf of our latest breast cancer booklet. See also our genetics and breast cancer and breast health pages.

On this page:

Breast tissue

Breast cancer

Causes of breast cancer

A family history and genetic testing

How common is breast cancer?

Breast tissue

Breast tissue is made up of milk glands, supportive fibrous tissue, fatty tissue, arteries, veins, lymph vessels and nerves. The milk glands consist of lobules, where milk is made, and ducts, which take the milk to the nipple. In women, breasts develop and change through their life under the influence of the hormones normally produced by the ovary.

Men also have breast tissue. 

Breast cancer

Breast cancer is a malignant tumour which starts in breast tissue. There are several types of breast cancer. They all begin in the milk ducts and/or the milk lobules (see diagrams below).

Some breast cancers are found when they are ‘in situ'. This means they have not spread outside the duct or lobule where they
began. However, most breast cancers are found when they are ‘invasive'. This means the cancers have grown beyond the duct or
lobule into other breast tissue or out of the breast.

Breast cancer which spreads out of the breast may also spread to lymph nodes in the armpit nearest the breast affected by cancer (axillary lymph nodes).

Breast cancer which is found before it appears to have spread beyond the breast and axillary lymph nodes is known as early breast cancer.

This information is mostly about early breast cancer. Breast cancer that has spread to other parts of the body, such as the bones and liver, is known as advanced breast cancer. If you would like information about advanced breast cancer, please contact the Cancer Council Helpline on 13 11 20.

 A diagram of the breast

Causes of breast cancer

The exact cause of breast cancer is not known. The risk of getting breast cancer increases:

  • as you get older: most breast cancer occurs in women over the
    age of 50
  • if you have a strong family history of breast cancer
  • if you have had breast cancer before
  • if you have had certain breast conditions (such as atypical ductal hyperplasia and lobular carcinoma in situ).

Some other factors that may increase a woman's risk by a small amount include:

  • not having children, or having children after the age of 30
  • early age at first period
  • later age at natural menopause (55 years or older)
  • alcohol
  • obesity or gaining a lot of weight after menopause
  • using the contraceptive pill - the risk is higher while taking the pill and for about 10 years after stopping use
  • using hormone replacement therapy - the risk increases the longer you take it, but disappears within about 2 years of
    stopping use. 

Having some of these risk factors does not mean that you will get breast cancer. Most women with breast cancer have no known risk factors.

In men, the main risk factor is abnormal enlargement of the breasts (gynaecomastia), due to drug, chemical or hormone treatments, or because of Klinefelter's syndrome. Men's risk increases where there is a family history of male breast cancer or a
strong family history of breast cancer.

A family history and genetic testing

A family history and genetic testing Some cases of breast cancer (about 5%) are thought to be due to an inherited gene change. Women in families with this inherited gene change could also be at more risk of ovarian cancer.

Men in these families may also be at more risk of breast cancer and prostate cancer.

People with a strong family history of breast cancer can be tested to see if they have inherited a gene change. There are reasons for and against being tested. If you would like to know more, ask your doctor about the Victorian Family Cancer Genetics Service or contact the Cancer Council Helpline on 13 11 20.

How common is breast cancer?

One in 11 Australian women will develop breast cancer at some time. Although it occurs in younger women, it is most common in women over the age of 50. In Victoria, around 3000 women are diagnosed each year.

Men can develop breast cancer. In Victoria about 20 men are diagnosed every year.


Back to top

  • Call the Cancer Council Helpline on 13 11 20 and talk to a trained professional
  • Relay for life - The Cancer Council's team fundraising event
    • A hugely popular relay-style event that raises money for cancer research.

  • Donate to The Cancer Council online