Worldwide, one in every 10 new cancers diagnosed yearly is breast cancer, and it is the principal cause of death among women in both developed and underdeveloped countries. For those reasons, we hear a great deal about this disease - its causes, diagnosis and treatment - and what we hear can frighten us. Knowledge can reduce the alarm, and it can also give us the tools to protect ourselves, our sisters, daughters, mothers and friends from the devastation and heartbreak of breast cancer.

The Anatomy of Breasts

Women’s breasts are complicated structures, largely composed of connective tissue and fat, but they also contain milk ducts, lymph nodes, blood vessels and tiny, milk-producing lobes and lobules.

While breasts vary in size dependent on their amount of fat, the functional areas that produce milk are very much the same in every woman. The lymph nodes found under the armpit, behind the breastbone and above the collarbone are crucial to general health, trapping and safely eliminating harmful substances.

Breast Cancer

Cancer begins with an uncontrolled growth of cells which can then travel from the original site to distant areas of the body. This proliferation must be controlled before it results in death. There are nearly 100 different types of cancer that affect different cells of the body.

Breast cancer, in general, is a cancer that begins in the breast tissue. However, there is more than one type of breast cancer, dependent on where it begins and how it progresses.

• Ductal carcinoma is the most common form of the disease and originates in the ducts that convey milk from the breast to the nipple. Ductal carcinoma in situ, or the point of origin, also called intraductal carcinoma or non-invasive cancer, develops in the lining of the milk ducts and, at the time of diagnosis, has not yet spread to other areas of the breast. Without treatment it may progress to invasive cancer.

• Lobular carcinoma starts in the lobules, the part of the breast that produces milk. It also appears in situ but is considered an indication of increased risk of invasive cancer in one or both breasts.

• HER2-positive breast cancer is a third form of cancer, named for the HER2 gene that assists cells in growing, dividing and repairing themselves. This is considered a more aggressive disease with a higher risk of recurrence after treatment.