What is breast cancer?

A breast is made up of three main parts: glands, ducts, and connective tissue. The glands produce milk. The ducts are passages that carry milk to the nipple. The connective tissue (which consists of fibrous and fatty tissue) connects and holds everything together. No breast is typical. What is normal for you may not be normal for another woman. Most women say their breasts feel lumpy or uneven. The way your breasts look and feel can be affected by getting your period, having children, losing or gaining weight, and taking certain medications. Breasts also tend to change as you age.

Breast lumps: Many conditions can cause lumps in the breast, including cancer. But most breast lumps are caused by other medical conditions. The two most common causes of breast lumps are fibrocystic breast condition and cysts. Fibrocystic condition causes noncancerous changes in the breast that can make them lumpy, tender and sore. Cysts are small fluid-filled sacs that can develop in the breast.

Breast Cancer: There are different kinds of breast cancer depending on which cells in the breast turn into cancer—cells in the ducts or those in the lobes. The most common are:

  • Ductal carcinoma. The most common kind of breast cancer, it begins in the cells that line the milk ducts in the breast, also called the lining of the breast ducts.
    • Ductal carcinoma in situ (DCIS). The abnormal cancer cells are only in the lining of the milk ducts, and have not spread to other tissues in the breast.
    • Invasive ductal carcinoma. The abnormal cancer cells break through the ducts and spread into other parts of the breast tissue. Invasive cancer cells can also spread to other parts of the body.

  • Lobular carcinoma. In this kind of breast cancer, the cancer cells begin in the lobes, or lobules, of the breast. Lobules are the glands that make milk.
    • Lobular carcinoma in situ (LCIS). The cancer cells are found only in the breast lobules. Lobular carcinoma in situ, or LCIS, does not spread to other tissues.
    • Invasive lobular carcinoma. Cancer cells spread from the lobules to the breast tissues that are close by. These invasive cancer cells can also spread to other parts of the body.

Breast Structure