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What is breast cancer?

Breast cancer is the abnormal growth of the cells lining the breast ducts or lobules. These abnormal cells 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).

Anyone can develop breast cancer. While it is much more common in women, men can also get breast cancer. Breast cancer in males is usually diagnosed and treated in the same way as it is for females. For more information for men diagnosed with breast cancer, visit breastcancerinmen.canceraustralia.gov.au or download Breast Cancer Network Australia’s Men get breast cancer too.

Transgender and gender-diverse people can also get breast cancer.

A transgender woman who is taking medicines to boost female hormones and lower male hormones may have an increased risk of developing breast cancer.

A transgender man who has a mastectomy is still at risk of developing breast cancer. This is likely due to small amounts of breast tissue that may remain after surgery.

What are the different types of breast conditions?

Non-invasive breast conditions
Also called carcinoma in situ. These are a precancerous condition where the cells look like cancer cells, but have not invaded nearby tissues.

ductal carcinoma in situ (DCIS)abnormal cells in the ducts of the breast; may develop into invasive breast cancer; treated in a similar way to invasive breast cancer, but chemotherapy is not used.
lobular carcinoma in situ (LCIS)abnormal cells in the lobules of the breast; increases the risk of developing cancer in either breast; needs regular mammograms or other scans.

Invasive breast cancer
There are two main types of invasive breast cancer. They are named after the area of the breast they start in.

invasive ductal carcinoma (IDC)starts in the ducts; accounts for about 80% of breast cancers.
invasive lobular carcinoma (ILC)starts in the lobules; makes up about 10% of breast cancers.

There are other less common types of breast cancer. These include inflammatory breast cancer, Paget’s disease of the nipple, medullary carcinoma, mucinous carcinoma and papillary carcinoma.

If invasive breast cancer spreads beyond the breast tissue and nearby lymph nodes, it is called advanced or metastatic breast cancer. For more information about metastatic breast cancer, call Cancer Council 13 11 20, or visit bcna.org.au or canceraustralia.gov.au.

How common is breast cancer?

Breast cancer is the most common cancer in Australian women (apart from common skin cancers). About 17,000 women are diagnosed with breast cancer each year, and one in eight will be diagnosed by the age of 85.

Although breast cancer 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% are diagnosed 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.

Learn more about the Breast Cancer Fund and the work we do in breast cancer research, prevention and support

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Understanding Breast Cancer

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This information is reviewed by

This information was last reviewed July 2020 by the following expert content reviewers: Prof Bruce Mann, Professor of Surgery, The University of Melbourne, and Director, Breast Tumour Stream, Victorian Comprehensive Cancer Centre, VIC; Dr Marie Burke, Radiation Oncologist, and Medical Director GenesisCare Oncology, QLD; Dr Susan Fraser, Breast Physician, Cairns Hospital and Marlin Coast Surgery Cairns, QLD; Ruth Groom, Consumer; Julie McGirr, 13 11 20 Consultant, Cancer Council Victoria; A/Prof Catriona McNeil, Medical Oncologist, Chris O’Brien Lifehouse, NSW; Dr Roya Merie, Staff Specialist, Radiation Oncology, Liverpool Cancer Therapy Centre, Liverpool Hospital, NSW; Dr Eva Nagy, Oncoplastic Breast Surgeon, Sydney Oncoplastic Surgery, NSW; Gay Refeld, Clinical Nurse Consultant – Breast Care, St John of God Subiaco Hospital, WA; Genny Springham, Consumer.