Breast Cancer

Breast cancer is a malignant tumor originating in the breast tissues. Like most cancers defined by the organ or structure of origin (e.g., lung, colorectal), breast cancer is not a single monolithic entity but rather a collection of diseases that arise in a single location.

The female breast comprises milk-producing lobules, ducts that transport the milk to the nipples, and stroma (i.e., fatty tissue, connective tissue, and blood and lymphatic vessels).1,2 Breast cancer types include ductal carcinoma, lobular carcinoma, inflammatory breast cancer, Paget’s disease of the nipple, phyllodes tumor, and angiosarcoma. Ductal and lobular carcinomas may be categorized as in situ, in which the cancer cells are contained within the originating structure, or as invasive/infiltrating, in which the tumor cells have grown past this structure into the surrounding tissues. Most breast cancers are ductal carcinomas, trailed in decreasing...