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Breast cancer

Breast Cancer

The Normal Breast

The female breast is made up of fat and milk glands. These glands are composed of basic units called lobules, and are drained by tubes (or ducts) that open at the nipple. The glandular part of the breast is in the middle and feels firmer than the surrounding fatty tissue (Figure 1). The anatomy of the breastThe anatomy of the breast.

The anatomy of the breast The anatomy of the breast

The relative proportions of milk glands, ducts and fat in the breast change with a woman's age and also during pregnancy. For example, the breast of a 25-year-old woman is mainly made up of milk glands, whereas, during pregnancy and breast-feeding, the number of milk glands increases substantially. The female sex hormone oestrogen acts on the breast to maintain the milk glands and ducts. During the menopause there is a decrease in the level of this hormone that causes the shrinkage of the glandular part of the breast. The glands are replaced by fat, which is why the breasts often feel softer after the menopause. Hormone replacement therapy helps to prevent these changes (see HRT). The breast also contains special channels called lymphatic vessels. These vessels transport fluid that accumulates between the cells and return it back into the blood circulation. The lymphatic vessels connect with lymph glands (also called lymph nodes). These are located all over the body. Most of the lymph glands draining the breast are found in the armpit. Cancer cells can spread along lymph vessels and into the lymph glands, causing them to enlarge.