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What is breast cancer?

What is breast cancer?


Cancer occurs as a result of abnormal changes in the genes that regulate the growth of cells in the body. These genes are located in the cell’s nucleus sometimes referred to as the ‘control centre’ of each cell. Normally, the cells in our body replace themselves in an orderly process of cell growth and repair (new cells replace old worn cells). But sometimes abnormal changes (mutations) can occur that ‘turn on’ certain genes and ‘turn off’ other genes in a cell. As a result, the changed cell develops the ability to keep dividing and growing in an uncontrolled way forming a cancerous or malignant tumour. The cancer cells if left unchecked may then spread into the surrounding tissue and to other parts of the body.

When cancer spreads into the body’s tissues, it is called invasive cancer. The site where cancer starts is called the primary cancer. Cancer that starts in the breast is called breast cancer and can develop at any age.

Breast cancer

Breast cancer is the abnormal growth of cells lining the breast lobules (milk-producing glands) and breast ducts (passages that drain milk from the lobules towards the nipple). Sometimes it can also begin in the fatty and fibrous tissue of the breast (see Figure 1: view of the female breast from the inside). The breast cancer cells grow uncontrollably and over time can spread into surrounding breast tissue. This is called ‘invasive breast cancer’ and has the potential to spread to other parts of the body.

Figure 1: View of the female breast from the inside

Types of breast cancer

Breast cancer - types and subtypes

Breast cancer is not one disease. There are different types and subtypes of disease that are referred to as breast cancer. This is why the treatment you receive for your breast cancer may be quite different to the other treatment women may have. Click here to read more.