Breast cancer is a malignant tumor that has developed from cells at that site. The disease occurs most frequently in women, and rarely in men. The breasts are glands protruding from the upper front chest wall. The breasts produce and release milk in women in association with pregnancy. They are composed of milk-secreting glands, ducts, and fatty, connective, and lymphatic tissue.
Lobules are the glands of women's breasts that can produce milk.
Ducts are the small passages connecting the milk-producing glands, or lobules, to the nipple. There are many types of breast tumors. Benign breast tumors such as fibroadenomas or papillomas do not spread outside of the breast and are not life-threatening. Other tumors are malignant, which is another word for cancerous, and may become life-threatening. Understanding some of the key words used to describe various types of breast cancer is important.