Breast cancer

Monday 31 October, 2011

This information is about early breast cancer, for other types of breast cancer, visit Cancer Australia's website, or call 13 11 20. See also our genetics and breast cancer, breast reconstruction and prosthesis, breast cancer trials or breast health pages.

On this page: What is breast cancer? | Types | Symptoms? | Causes? | Inherited breast cancer gene | How common is it? | Weblinks | Reviewers

Women and men both have breast tissue. In women, breasts are made up of milk glands. The milk gland consists of lobules, where milk is made, and tubes called ducts that take milk to the nipples. In men, the development of the lobules is suppressed at puberty by testosterone, the male sex hormone.

Both female and male breasts contain supportive fibrous tissue and fatty tissue. Some breast tissue extends into the armpit (axilla). This is known as the axillary tail.

The armpits contain a collection of lymph nodes (also called lymph glands), which are part of the lymphatic system. The lymphatic system is part of the immune system and protects the body against disease and infection. 

A diagram of the breast

What is breast cancer?

Breast cancer occurs when the cells lining the breast ducts or lobules grow abnormally and out of control. A tumour can form in the ducts or lobules of the breast.

Women and men can both get breast cancer, although it is rare in men. Men's symptoms are similar to women's.

Types of breast cancer

When the cells that look like breast cancer are still confined to the ducts or lobules of the breast, it is called pre-invasive breast cancer. The most common type of pre-invasive breast cancer is ductal carcinoma in-situ (DCIS).

Most breast cancers are found when they are invasive. This means the cancer has spread outside the ducts or lobules of the breast into surrounding tissue. The most common types are invasive ductal cancer (IDC) and invasive lobular cancer (ILC). There are several categories of invasive breast cancer:

Early breast cancer: Cancer cells are found in the breast and may have spread to lymph nodes in the armpit.

Locally advanced breast cancer: The cancer has spread to places near the breast, such as the chest (including the skin, muscles and bones of the chest), but it isn't found in other areas of the body.

Metastatic breast cancer - Cancer cells have spread from the breast to other areas of the body, such as the bones, liver or lungs. This is also called advanced breast cancer.

Some women have abnormal cells in the lobules of the breast. This is called lobular carcinoma in-situ (LCIS). LCIS is not cancer but if you have it, you may be at an increased risk of developing cancer. Your medical team will monitor you with regular mammograms.


Symptoms of breast cancer

You may notice a change in your breast or your doctor may find an unusual breast change during a physical examination. Signs to look for include:

  • a lump, lumpiness or thickening
  • 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 of the skin, unusual redness or other colour changes
  • an increase or decrease in the size of the breast
  • a change to the shape of the breast
  • swelling or discomfort in the armpit
  • persistent, unusual pain that is not related to your normal monthly menstrual cycle, remains after a period and occurs in one breast only.

Changes to your breast don't necessarily mean you have breast cancer. However, if you have any symptoms, have them checked by your doctor without delay.

Some women have no symptoms and the breast cancer is found on a screening mammogram.

Women aged 50-69 should have regular screening mammograms through BreastScreen. Call 13 20 50 for a free appointment. However, women should understand the limitations of the test and make an informed personal choice about taking part in breast screening.

Causes of breast cancer

The exact cause of breast cancer is not known, but some factors increase the risk:

  • getting older (most common in women over 50)
  • having several close relatives, such as a mother, father, sister or daughter, diagnosed with breast cancer - these relatives can be from either the mother's or father's side of the family
  • if you have had breast cancer before
  • if you have had certain breast conditions such as atypical ductal hyperplasia or lobular carcinoma in-situ.

Having some of these risk factors does not necessarily mean that you will develop breast cancer. Most women with breast cancer have no known risk factors, aside from getting older.

In men, breast cancer usually occurs over the age of 60. It is most common in men who have:

  • several close family members (male or female) who have had breast cancer
  • a relative diagnosed with breast cancer under the age of 40
  • several relatives with cancer of the ovary or colon
  • a rare genetic syndrome called Klinefelter's syndrome. Men with this syndrome have three sex chromosomes (XXY) instead of the usual two (XY).

Inherited breast cancer gene

Each person inherits a set of genes from each parent. Sometimes there is a fault in one copy of a gene, which stops that gene working properly. This fault is called a mutation.

About one in 20 cases of breast cancer may be caused by an inherited gene fault. The two most common breast cancer genes are called BRCA1 and BRCA2.

Women in families with an inherited gene change are at an increased risk of breast and ovarian cancer. Men in these families may also be at an increased risk of breast and prostate cancer.

People with a strong family history of breast cancer can be tested to see if they have inherited a gene change. If you would like to know more about genetic testing, talk to your doctor or breast care nurse, or call Cancer Council Helpline 13 11 20.

How common is it?

Breast cancer is the most common cancer in Australian women. About 13,000 women are diagnosed each year. One in nine women will be diagnosed with breast cancer by the age of 85.

Breast cancer is rare in men. About 100 men are diagnosed in Australia each year. This represents less than 1% of all breast cancers.

Although it can occur at any age, breast cancer is more common in older women. The average age at diagnosis is 60. About one-quarter of women who are diagnosed are younger than 50 years of age. 


The web can be a useful source of information. The following sites are reliable sources:


Breast Cancer Network Australia

National Breast and Ovarian Cancer Centre


Macmillan Cancer Support

National Cancer Institute

Information reviewed by: Professor John Boyages, Executive Director, Westmead Breast Cancer Institute, Westmead Hospital and author, Breast Cancer: Taking Control; Lynn Buglar, Breast Physician, BreastScreen NSW; Bronwyn Chalmers, Cancer Information Consultant, Helpline, Cancer Council NSW; Susan Munro, McGrath Breast Care Nurse, Community Health/Wagga Wagga Base Hospital, Wagga Wagga; and Kathryn Rutkowski, Consumer.

Updated: 31 Oct, 2011