Types of Breast Cancer
Inflammatory Breast Cancer
Inflammatory breast cancer is a rare type of cancer that often does not cause a breast lump or mass. As seen in this photo, it often causes thickening and pitting of the skin, like an orange peel. The affected breast may also be larger or firmer, tender, or itchy. A skin rash or reddening of the skin is common. These changes are caused by cancer cells blocking lymph vessels in the skin. Inflammatory cancer of the breast typically has a fast growth rate.
Invasive Ductal Carcinoma
Invasive (or infiltrating) ductal carcinoma (IDC) is the most common type of breast cancer. About 80% of all breast cancers are invasive ductal carcinomas. Invasive ductal carcinoma refers to cancer that has broken through the wall of the milk ducts and has invaded the breast tissues. Invasive ductal carcinoma can spread to the lymph nodes and possibly to other areas of the body.
Ductal Carcinoma in Situ (DCIS)
Ductal carcinoma in situ (DCIS) is considered to be a non-invasive or pre-invasive breast cancer. Ductal means that the cancer starts inside the milk ducts, carcinoma refers to any cancer that starts in the skin or other tissue (including breast tissue) that line or cover the internal organs, and in situ means “in its original place.” The difference between DCIS and invasive cancer is that in DCIS, the cells have not spread through the walls of the milk ducts into the surrounding breast tissue.. DCIS is considered a ‘pre-cancer’, but some cases can transform into more invasive cancers.
Invasive Lobular Carcinoma
Invasive (or infiltrating) lobular carcinoma (ILC) is the second most common type of breast cancer after invasive ductal carcinoma. Lobular means that the cancer started in the milk-producing lobules, which empty out into the ducts that carry milk to the nipple. Invasive lobular carcinoma refers to cancer that has broken through the wall of the lobule and begun to invade the breast tissues. Invasive lobular carcinoma can spread to the lymph nodes and possibly to other areas of the body.
Mucinous (or colloid) carcinoma of the breast is a rare form of invasive ductal carcinoma. In this type of cancer, the tumor is composed of abnormal cells that “float” in pools of mucin, part of the slimy, slippery substance known as mucus. Mucus lines most of the inner surface of our bodies, such as our digestive tract, lungs, liver, and other vital organs. Breast cancer cells can produce some mucus. In mucinous carcinoma, mucin becomes part of the tumor and surrounds the breast cancer cells.
“Pure” mucinous carcinomas make up only 2-3% of invasive breast cancers. Approximately 5% of invasive breast cancer tumors have a mix of mucinous components in addition to other types of breast cancer cells.
Triple-Negative Breast Cancers
Testing negative for estrogen receptors (ER-), progesterone receptors (PR-), and HER2 (HER2-) on a pathology report means the cancer is “triple-negative”. These negative results indicate the growth of the cancer is not supported by the hormones estrogen and progesterone, nor by the presence of too many HER2 receptors. Therefore, triple-negative breast cancer does not respond to hormonal therapy (such as tamoxifen or aromatase inhibitors) or therapies that target HER2 receptors, such as Herceptin. However, other medicines can be used to treat triple-negative breast cancer.
Paget’s Disease of the Nipple
Paget's disease of the nipple is a rare form of breast cancer in which cancer cells collect in or around the nipple. The cancer usually affects the ducts of the nipple first then spreads to the nipple surface and the areola. A scaly, red, itchy, and irritated nipple and areola are signs of Paget’s disease of the nipple. One theory for the cause of Paget’s disease is that the cancer cells start growing inside the milk ducts within the breast and then break through to the nipple surface. Another possibility is that the cells of the nipple itself become cancerous.