Picture of the breasts
A woman's breasts are important for breastfeeding babies and also play a part in sexual arousal.
There are conditions which can affect the breasts, causing pain and discomfort, as well as the risk of breast cancer.
The NHS advises women to be 'breast aware' and to check their breasts regularly for any unusual changes, such as a lump.
The breast is the tissue overlying the chest (pectoral) muscles. Women's breasts are made of specialised tissue that produces milk (glandular tissue) as well as fatty tissue. The amount of fat determines the size of the breast.
The milk-producing part of the breast is organised into 15 to 20 sections, called lobes. Within each lobe are smaller structures, called lobules, where milk is produced. The milk travels through a network of tiny tubes called ducts. The ducts connect and come together into larger ducts, which eventually exit the skin in the nipple. The dark area of skin surrounding the nipple is called the areola.
Connective tissue and ligaments provide support to the breast and give it its shape. Nerves provide sensation to the breast. The breast also contains blood vessels, lymph vessels and lymph nodes.
Breast cancer: Malignant (cancer) cells multiplying abnormally in the breast, eventually spreading to the rest of the body if untreated. Breast cancer occurs almost exclusively in women, although men can be affected. Signs of breast cancer include a lump, bloody nipple discharge or skin changes.
Ductal carcinoma in situ (DCIS): Breast cancer in the duct cells that has not invaded deeper or spread through the body. Women diagnosed with DCIS have a high likelihood of being cured.
Lobular carcinoma in situ (LCIS): Although called a carcinoma LCIS, which occurs in the milk-producing lobule cells, this condition does not invade or spread and is not a true cancer. However, women with LCIS have an increased likelihood of developing invasive breast cancer in the future.
Invasive ductal carcinoma: Breast cancer that begins in the duct cells but then invades deeper into the breast, carrying the potential of spreading to the rest of the body (metastasising). Invasive ductal carcinoma is the most common type of invasive breast cancer.
Invasive lobular carcinoma: Breast cancer that begins in the milk-producing lobule cells, but then invades deeper into the breast, carrying the potential of spreading to the rest of the body (metastasising). Invasive lobular carcinoma is an uncommon form of breast cancer.
Simple breast cyst: A benign (noncancerous), fluid-filled sac that commonly develops in women in their 30s or 40s. Breast cysts may cause tenderness and may be drained.
Breast fibroadenoma: A very common noncancerous solid tumour of the breast. A typical fibroadenoma creates a painless, mobile lump in the breast and most commonly occurs in women in their 20s or 30s.