Breast Cancer (Carcinoma of the Breast)

What is Breast Cancer?

Adenocarcinoma of the breast is a form of breast cancer originating in the milk ducts and/or lobules (glandular tissue) of the breast. The breast is an organ composed mainly of fatty tissue which also has milk glands contained within it. A series of ducts connect the milk glands to the nipple. The breast is rich in blood vessels and lymphatic channels.

Breast diseases such as breast cancer predominantly affect women. This is because male breasts are more rudimentary than female breasts, making them more resistant to cancer. Breast cancer is sometimes classified into several 'types'. The major types are:

Ductal carcinoma (70-80%): cancer cells that resemble the ducts of the breast
Lobular carcinoma (5-10%): cancer cells that resemble the lobules or glands of the breast
Medullary carcinoma (1 to 5%)
Mucinous carcinoma (1 to 6%)
Tubular carcinoma (2%)

Some features are common to all types of breast cancers. The difference between the different types is mainly in terms of breast cancer prognosis.

Statistics on Breast Cancer?

Breast cancer is the most common type of cancer affecting Australian women. It is also the leading cause of cancer death in Australian women.

The incidence of breast cancer increases with age. It is relatively rare under the age of 30, but by 75 years of age as many as 1 in 11 women will have been diagnosed with breast cancer. The average age at diagnosis is 60 years.

Breast cancer is found throughout the world. Australia's rate of incidence of breast cancer is similar to that of other developed countries, including Canada, the UK, the United States of America and New Zealand.

Risk Factors for Breast Cancer

The main risk factors for breast cancer are:

Increasing age;
A family history of breast cancer;
Hormonal factors: women who begin menstruation early, have a late menopause, or have late or few pregnancies;
Obesity; and
Excess alcohol use (daily consumption of >2 standard drinks).

There is also some evidence that long-term hormone therapy (for example the use of the oral contraceptive pill or hormone replacement therapy (HRT)) may increase the risk of breast cancer.

Progression of Breast Cancer

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In some cases, invasive breast carcinoma is preceded by an earlier, 'pre-cancerous' condition known as ductal carcinoma in situ (DCIS) or lobular carcinoma in situ (LCIS). In these 'in situ' carcinomas, cells of the ducts or lobules of the breast have developed the ability to multiply out of control - one of the characteristics of cancer. However, the cells of in situ carcinoma have not developed the ability to spread beyond the lobules of the breast, as they do in invasive cancer, and instead remain 'in situ', or in place.

If carcinoma in situ is detected early, for example through mammographic screening, then treatment of carcinoma in situ may prevent development of invasive breast cancer.

How is Breast Cancer Diagnosed?

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Any new breast symptom, such as a lump, is assessed with the 'triple test'. This includes examination of the breast, imaging of the breast through mammography or ultrasound, and sampling of the breast tissue with fine needle aspiration (FNA), core biopsy or open biopsy.

Following a diagnosis of breast cancer, blood tests including Full Blood Count and Liver Function Tests may be used to assess the possibility that the cancer may have spread to the liver or bone marrow. Other imaging tests, including chest x-rays, bone scan, abdominal CT or liver ultrasound may also be used if symptoms suggest that the cancer has spread.

More information

For more information on breast cancer, types of breast cancer and its investigations and treatments, as well as some useful videos, see Breast Cancer.

Prognosis of Breast Cancer

Early breast cancer has a good (greater than 80%) 5 year survival. Important prognostic factors which can help predict survival include involvement of lymph nodes, the size of the tumour, and how aggressive the tumour cells are. If the cancer has metastasised (spread) to lung, liver or bone at diagnosis, 5-year survival rates are significantly lower.

Breast cancers in Australia are 'staged' based on the TNM (Tumour, Node, Metastasis) system. 'Early' breast cancer refers to Stage I, and some Stage II only.

Breast Cancer References

Australian Institute of Health and Welfare & National Breast Cancer Centre 2006. Breast cancer in Australia: an overview, 2006. Cancer series no. 34. cat. no. CAN 29. Canberra: AIHW.
Braunwald, Fauci, Kasper, Hauser, Longo, Jameson. Harrison's Principles of Internal Medicine. 16th Edition. McGraw-Hill. 2001
Cotran RS, Kumar V, Collins T. Robbins Pathological Basis of Disease Sixth Ed. WB Saunders Company 1999.
Dr Guy Van Hazel, Oncologist, Mount Hospital, Perth
Kumar P, Clark M. Clinical Medicine. Fourth Ed. WB Saunders, 1998.
National Breast Cancer Centre. 2003. 'The clinical management of ductal carcinoma in situ, lobular carcinoma in situ and atypical hyperplasia of the breast,' First Edition. National Breast Cancer Centre, Camperdown, NSW. [online] Available from: http://www.nbcc.org.au/bestpractice/resources/CMW_dcisbook.pdf
National Breast Cancer Centre. 2001. 'Clinical practice guidelines for the management of early breast cancer:Second edition'. National Breast Cancer Centre, Camperdown,NSW. [online] Available from: http://www.nhmrc.gov.au/publications/synopses/cp74syn.htm
National Breast Cancer Centre. 2003. 'A guide for women with early breast cancer.' National Breast Cancer Centre, Camperdown, NSW. [online] Available from: http://www.nbcc.org.au/resources/documents/EBC_earlyguide.pdf