Breast cancer is a malignant form of cells that grow outside the normal cell cycle in the breast. This cancer is the leading form of cancer affecting women (after skin cancers), according to the American Cancer Society, and it is the second leading cause of cancer death in women in the United States (after lung cancer). Cancers can be either sarcomas or carcinomas; most breast cancers are carcinomas. Sarcomas start in the connective tissues, and carcinomas start in the lining layer that covers the actual organ, in this case, the breast. Breast cancer is divided into two main categories: invasive and non-invasive. Understanding the type of breast cancer helps the physician know the extent of it and how best to treat it.
Non-Invasive
Non-invasive breast carcinomas are usually referred to as "in situ," meaning they are confined to the superficial tissues in the breast. These types are ductal and lobular, and are easier to treat. Most women with ductal in situ carcinomas can be cured, but those with lobular in situ carcinomas usually have a high risk of developing invasive cancer in the other breast.
Invasive
Invasive breast carcinomas are the deadly types, as they can spread into the deeper tissues and other organs. The two main invasive carcinomas are invasive ductal carcinoma and invasive lobular carcinoma. Ductal carcinoma is the most common form. It begins in the duct of the breast (where the milk passes through) and spreads through the wall of the duct into the breast fatty tissue. It then metastasizes through the lymphatic system and bloodstream to other organs in the body. Lobular carcinoma starts in the lobules (where milk is produced) and metastasizes as well. It has the ability to go undetected in a mammogram screening.
Less Common Types
Other types of less common breast carcinomas include medullary, metaplastic, mucinous, tubular, papillary and adenocystic carcinomas. Those with a better prognosis upon diagnosis are mucinous and adenocystic carcinomas. Women diagnosed with these usually have a positive recovery outlook. In addition to undergoing chemotherapy, most physicians usually encourage removing the breast through mastectomy, even in carcinomas with good prognosis.
