There are several different types of breast cancer that are differentiated according to their location, whether they are invasive, non-invasive, or metastatic, if they are a molecular subtype of a particular type of breast cancer, and other characteristics. Invasive breast cancer occurs when cancer spreads to other parts of the breast, while non-invasive breast cancer remains in one part of the breast. In comparison, metastatic breast cancer occurs when cancer spreads beyond the breast to other body parts. Molecular subtypes of breast cancer are when particular characteristics on a cellular or molecular level of the tumor set it apart from standard breast cancer types. With that in mind, the different types of breast cancer and their distinguishing characteristics are as follows: - Ductal Carcinoma In Situ (DCIS): non-invasive breast cancer that begins inside the milk ducts. If DCIS spreads beyond the milk ducts, it is called Invasive Ductal Carcinoma (IDC). Subtypes of IDC include Tubular Carcinoma, Medullary Carcinoma, Mucinous Carcinoma, Papillary Carcinoma, and Cribriform Carcinoma. - Inflammatory Breast Cancer: a rare and aggressive type of breast cancer that begins with redness and swelling in the breast tissue rather than a lump. - Lobular Carcinoma In Situ (LCIS): abnormal cell growth in the lobules, or milk-producing glands at the end of the breast ducts. If the lobular cell growth becomes invasive, it is called Invasive Lobular Carcinoma (ILC). Subtypes of ILC include alveolar carcinoma, pleomorphic carcinoma, signet ring cell carcinoma, solid carcinoma, and tubulolobular carcinoma. - Male Breast Cancer: a rare type of breast cancer where that affects male breast tissue. - Metastatic Breast Cancer: also called Stage IV breast cancer, metastatic breast cancer occurs when cancer spreads other parts of the body, such as the brain, bones, liver, or lungs. - Paget’s Disease of the Nipple: a rare form of breast cancer where the cancer cells collect in and around the nipple, typically starting in the nipple ducts before spreading to the nipple surface and areola. - Phyllodes Tumors of the Breast: a rare type of breast cancer that is typically invasive or non-invasive and occurs when the tumors grow in leaflike patterns. - Recurrent Breast Cancer: occurs when breast cancer returns to the same or opposite breast after being undetectable for some time. - Triple-Negative Breast Cancer: cancer that tests negative for estrogen receptors, progesterone receptors, and HER2 protein receptors.