Another step in educating yourself about breast cancer is to learn about the different types. There are many different breast cancer types, but the vast majority (over 80%) begins in either the milk ducts or the lobular (milk-producing) tissue. These two types of breast cancer are called ductal carcinoma and lobular carcinoma . Either breast cancer type, if diagnosed early enough, may be called " in situ ", which means that the cancer has not invaded surrounding fatty tissues in the breast nor spread to other organs in the body. The outcome for the invasive or infiltrating version of either breast cancer type depends on many factors, such as the stage of the cancer, your age, and your general health.

There are also some other breast cancer types which appear in a less percentage of all types of breast cancers:

• Medullary carcinoma. This type of infiltrating breast cancer accounts for about 5% of breast cancers. It has a rather well-defined, distinct boundary between tumor tissue and normal tissue and special features, including the large size of the cancer cells and the presence of immune system cells at the edges of the tumor.

• Inflammatory breast cancer. This type of invasive breast cancer accounts for about 1% to 3% of all breast cancers. It makes the skin of the breast look red and feels warm and gives the skin a thick, pitted appearance.

• Tubular carcinoma. Tubular carcinomas are a special type of infiltrating breast carcinoma. They account for about 2% of all breast cancers and have a better prognosis than infiltrating ductal or lobular carcinomas.

• Paget's disease of the nipple. This breast cancer type starts in the breast ducts and spreads to the skin of the nipple and then to the areola, the dark circle around the nipple. It accouns only 1% of all cases of breast cancer. The skin of the nipple and areola often appears crusted, scaly, and red, with areas of bleeding or oozing. The woman may notice burning or itching.