What is breast cancer?
Breast cancer starts in the ducts or lobules of the breast. Cells lining the ducts or lobules can grow out of control and develop into cancer.
Some breast cancers are found when they are still confined to the ducts or lobules of the breast. This is called pre-invasive breast cancer. The most common types are ductal carcinoma in situ (DCIS) and lobular carcinoma in situ (LCIS).
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.
There are several categories of invasive breast cancer.
- Early breast cancer: contained in the breast but may have spread to one or more lymph nodes in the armpit.
- Locally advanced breast cancer: may have spread to places near the breast, such as the chest (including the skin, muscles or bones of the chest), but the cancer isn’t found in other areas of the body.
- Metastatic breast cancer: the cancer cells spread from the breast to other areas of the body, such as the bones, liver or the lungs. It may also be called advanced breast cancer.
This booklet is about early breast cancer. For information on other categories of breast cancer visit the National Breast and Ovarain Cancer Centre’s website, www.nbocc.org.au or call the Cancer Council Helpline on 13 11 20. |
How common is it?
Breast cancer is the most common cancer in Australian women. One in 8 women will be diagnosed with breast cancer by the age of 85. Around 13,000 women are diagnosed with breast cancer each year.
Breast cancer can occur at any age. It is more common in women aged over 60 but around one-quarter of women are younger than 50.
Men can also develop breast cancer, although this is rare. Around 110 men are diagnosed each year in Australia.
What are the causes?
The exact cause of breast cancer is not known, but some factors increase the risk:
- getting older
- having several close relatives, like a mother, 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, ductal carcinoma in situ or lobular carcinoma in situ.
Having some of these risk factors does not 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 members of their family (male or female) who have had breast cancer
- a relative diagnosed with breast cancer under the age of 40
- several members of the family 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
A set of genes is inherited 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.
A small number of breast cancers (about 5% or 1 in 20) may be caused by an inherited gene fault. Two breast cancer genes have been found: BRCA1 and BRCA2.Women in families with an inherited gene change could be at increased risk of ovarian cancer. Men in these families may also be at increased 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.
More information
- Call the Cancer Council Helpline on 13 11 20.
