Outlook Breast cancer is the most common invasive cancer in women, and the second main cause of cancer death in women, after lung cancer. Advances in screening and treatment have improved survival rates dramatically since There are around 3. The chance of any woman dying from breast cancer is around 1 in 37, or 2.
Each breast contains between 15 and 20 sections called lobes, each of which is composed of many smaller structures known as glands or alveoli. These glands produce milk. A system of small tubes known as ducts transports milk from the glands to a big central duct that has multiple openings in the nipple. A central duct opens into the nipple from each lobe. A band of muscle surrounds each gland. Eventually, a sucking baby extracts the milk by pressing and pumping it out from these pools through the nipple.
Skin In women, the breasts overlie the pectoralis major muscles and usually extend from the level of the second rib to the level of the sixth rib in the front of the human rib cage ; thus, the breasts cover much of the chest area and the chest walls. At the front of the chest, the breast tissue can extend from the clavicle collarbone to the middle of the sternum breastbone. At the sides of the chest, the breast tissue can extend into the axilla armpit , and can reach as far to the back as the latissimus dorsi muscle , extending from the lower back to the humerus bone the longest bone of the upper arm. As a mammary gland , the breast is composed of differing layers of tissue , predominantly two types:
Some breast lumps feel as though they have a distinct border, while others may feel like a general area of thickened tissue. Noncancerous lumps The size, feel, and texture of breast lumps can vary differ considerably. The consistency may help a physician to diagnose what kind of a lump it is. Breast cysts A breast cyst is a benign, or noncancerous, fluid-filled sac in the breast.