This factsheet gives information about the diagnosis and treatment of breast cancer. Breast cancer can affect both women and men. This factsheet is aimed mainly at women, as very few cases of breast cancer occur in men. However, the treatments used are the same.

The breasts are made up of fat, connective tissue and glandular tissue, and are divided into lobes. The lobes are where breast milk is produced. A network of ducts (fine tubes) connect the lobes to the nipple. When a woman has had a baby the breasts produce milk which then passes down the ducts and out of the nipple to feed the baby.

A woman’s breasts are rarely the same size as each other. They may feel different at different times of the menstrual cycle. Sometimes the breast can become lumpy just before a period.

Under the skin, some of breast tissue extends into the armpit. The armpits also contain a collection of lymph glands or nodes which make up part of the lymphatic system. The lymphatic system is a network of lymph glands connected throughout the body by tiny vessels called lymph vessels. Flowing through the lymphatic system is lymph fluid. It contains cells called lymphocytes, which are designed to fight disease.

The organs and tissues of the body are made up of tiny building blocks called cells. Cancer is a disease of these cells. Although cells in different parts of the body may look and work differently, most repair and reproduce themselves in the same way. Normally, this division of cells takes place in an orderly and controlled manner. If, for some reason, the process gets out of control, the cells will continue to divide, developing into a lump which is called a tumour. Tumours of the breast are usually caused by overgrowth of the cells lining the breast ducts. They can be either benign or malignant.

In a benign tumour, the cells grow abnormally and form a lump. But they do not spread to other parts of the body and so are not cancerous. The commonest type of benign breast tumour is called a ‘fibroadenoma’. These often need to be surgically removed to confirm the diagnosis. No other treatment is necessary.

A malignant tumour consists of cancer cells which have the ability to spread beyond the breast if they are left untreated. If a malignant tumour in the breast is not treated it may grow into the muscles which lie under the breast. It can also grow into the skin covering the breast. Sometimes cells break away from the original (primary) cancer and spread to other organs in the body. They can spread through the bloodstream or lymphatic

system (see page 00). When these cells reach a new area they may form a new tumour. The new tumour is often called a secondary or metastasis.

Breast cancer occurs when cells within the breast ducts and lobules become cancerous. If caught at an early stage, breast cancer can often be cured. However if the cancer has spread to other areas of the body it cannot usually be cured, but treatment can often still be given to control the cancer for months or years.