What Is Breast Cancer?
A woman's breast is fully developed when she is in her twenties. The female breast is made up of milk glands and ducts and is surrounded by a layer of fat. Each female breast contains about 12 to 15 milk glands. Milk is produced in the milk glands and collects in small ducts. These join together to form larger ducts, which eventually drain via the nipples.
During a woman's reproductive period (approximately between 20 and 40 years old), the breast is affected by female hormones, whose levels vary with the menstrual cycle. This can cause the breast to become tender, hard, or lumpy, especially during the premenstrual phase. When a woman enters her thirties, the milk glands and ducts in her breast become smaller and are replaced by fibrous and fatty tissue. Breast cancer commonly develops within these milk ducts and glands.