disease

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:

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

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. You can see an example of this in the image of lobular carcinoma in situ, below. 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. Once breast cancer has developed the ability to grow and spread throughout the breast, there is a risk that it will metastasise (spread) to lymph nodes or other organs in the body. Invasive ductal carcinoma of the breast usually spreads first by direct invasion of overlying skin and adjacent fat, direct spread into lymphatics and from there to lymph nodes in the axilla (armpit), neck and supraclavicular region. If cancerous cells enter the bloodstream, deposits may be found in the bones, lung, and brain.

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, 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. This staging system can be used to work out the prognosis (probable outcome) and best treatment options for cancer of different stages. In this system, 'Tumour' refers to tumour size, which is measured in centimetres. 'Node' refers to the presence of cancerous cells in regional lymph nodes. 'Metastasis' refers to the spread of cancer beyond regional lymph nodes to other organs of the body.

Using this classification, cancers are grouped into stages as follows:

1.  non-invasive breast cancer, including lobular carcinoma in situ and ductal carcinoma in situ.
2.  invasive breast cancer. The tumour may measure up to 2 cm, and no lymph nodes are involved.
3.  the cancer measures between 2 and 5cm, or involves lymph nodes on the same side of the body as the cancer.
4.  the tumour has grown larger than 5cm; there is significant lymph node involvement with 'fixing' or 'matting' of the nodes; or a tumour of any size has spread to the skin, chest wall, or internal mammary lymph nodes.
5. the cancer has spread beyond the breast, underarm, and internal mammary lymph nodes.

Early' breast cancer refers to Stage I, and some Stage II only.