Carcinoma of the Breast

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What is Carcinoma of the Breast?

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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.

Who gets Carcinoma of the Breast?

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.

Predisposing Factors

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

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.

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