Breast cancer, or breast carcinoma, is an uncontrolled growth of epithelial cells within the breast. It’s the second most common cancer in women, but can also, on rare occasion, affect men as well.
Breast cancer is also the second leading cause of cancer deaths in women after lung cancer. This is largely due to the fact that oftentimes breast cancers don’t cause any pain or discomfort until they’ve spread to nearby tissues.
The breasts are milk-producing glands that sit on the chest wall, on either side of the breast-bone. They lie on top of the ribs and the pectoral muscles, and they’re divided into three main parts.
The glandular tissue that makes the milk, is made up of 15 to 20 lobules. Inside each of these lie a bunch of grape-like structures called the alveoli, which are modified sweat glands surrounded by a basement membrane made largely of collagen.
Zooming in on the alveoli, there’s a layer of alveolar cells that secrete breast milk into the lumen which is the space in the center of the gland.
Wrapping around the alveolus are special myoepithelial cells that squeeze down and push the milk out of the lumen of the alveolus, down the lactiferous ducts, and out one of the pores on the nipple.
Now, surrounding the glandular tissue is the stroma, which contains adipose or fat tissue, and this makes up the majority of the breast.
Suspensory ligaments called Cooperʼs ligaments, run through the stroma and help keep it in place. These ligaments attach to the inner surface of the breast skin on one end and the pectoralis muscles on the other.
Just below the skin over the breast, there’s a network of tiny lymphatic vessels that drain the lymph, which is a fluid containing cellular waste products and white blood cells. These lymphatic vessels mainly drain into a group of lymph nodes in the axilla, or the armpit.