Breast Anatomy


As you learn about breast cancer, we will repeatedly reference the anatomy of the breast. Understanding the different parts and functions will help you better grasp the details of breast cancer.

Knowing your body helps you to:

  • Make informed decisions.
  • Have a better dialogue with your doctor.
  • Be aware of anything unusual.

Adipose tissue

The female breast is mostly made up of a collection of fat cells called adipose tissue. This tissue extends from the collarbone down to the underarm and across to the middle of the ribcage.

Lobes, lobules, and milk ducts

A healthy female breast is made up of 12–20 sections called lobes. Each of these lobes is made up of many smaller lobules, the gland that produces milk in nursing women. Both the lobes and lobules are connected by milk ducts, which act as stems or tubes to carry the milk to the nipple. These breast structures are generally where the cancer begins to form.

The Lymph System

Within the adipose tissue is a network of ligaments, fibrous connective tissue, nerves, lymph vessels, lymph nodes, and blood vessels.

The lymph system, which is part of the immune system, is a network of lymph vessels and lymph nodes running throughout the entire body. Similar to how the blood circulatory system distributes elements throughout the body, the lymph system transports disease-fighting cells and fluids. Clusters of bean-shaped lymph nodes are fixed in areas throughout the lymph system and act as filters by carrying abnormal cells away from healthy tissue.

The type of breast cancer is generally determined by the origin of the growth of cancer cells, which is almost always in the lobes, lobules, or ducts. When cancer is found in the nearby lymph nodes, it helps doctors identify just how far the cancer has spread. If the nearest nodes contain cancer, additional nodes are usually examined for the presence or absence of cancer cells to understand how far the disease has progressed.