Breast Cancer

Doctors determine the types of breast cancers according to which areas they develop and spread.

Breast cancer is a type of carcinoma that originates in the breast tissue and is considered an adenocarcinoma (cancerous cells that line organs such as breasts, lungs, prostate, colon, esophagus, or pancreas).

The earliest stage of ductal carcinoma (cancer that starts in the milk ducts) is carcinoma in situ (DCIS). The term "in situ" refers to the cancer being limited to the milk ducts. This form of breast cancer is also noninvasive, meaning it is unlikely to spread to other body areas. Ductal carcinoma is highly curable and occurs in about 1 in 5 people who are diagnosed with breast cancer.

Another type of ductal carcinoma is invasive ductal carcinoma (IDC). Considered to be the most common type of breast cancer, IDC affects about 80% of those diagnosed with breast cancer. The word "invasive" refers to cancer spreading beyond the milk ducts where it originated.

Invasive ductal carcinomais divided into subtypes:

• Medullary carcinoma - A rare, invasive breast cancer affecting less than 5% of diagnosed breast cancers. Medullary carcinoma is named because it resembles the gray matter tissue of the brain's medulla.
• Mucinous carcinoma - Also known as colloid carcinoma, this type of cancer affects about 2% of breast cancers. It occurs when the "mucin" contained in mucus becomes too abundant surrounding a cell.
• Tubular carcinoma - This type of breast cancer grows slowly and is treatable. It gets its name from the tube-shaped formations inside the cancer cells. This type of cancer accounts for 1-2% of invasive breast cancers.
• Papillary carcinoma - Named for the papules (finger-like growths) that poke through the cancer cells, this type of breast cancer affects about 1% of cases. The majority of those affected are older women.
• Cribriform carcinoma - This type of breast cancer is rare and affects about 5-6% of invasive breast cancers. It is recognized by the distinct pattern of holes in between the cancer cells.

Lobular carcinoma, also known as infiltrating lobular carcinoma (ILC),is the second most common invasive cancer affecting about 10% of invasive breast cancers. In this type of cancer, a missing protein means cells have trouble "sticking together." As a result, this cancer can spread through breast tissue. If ILC spreads to the lymph nodes, it is transmitted to other body parts.

Inflammatory breast cancer is a rare, rapidly developing type of breast cancer. The affected breast often becomes swollen, red, and tender (and sometimes looks like an orange peel called peau d'orange). Inflammatory breast cancer forms when the lymphatic vessels located in the breast skin are blocked by cancer cells. Inflammatory breast cancer originates from nearby tissue, usually the point of origin, and often advances to lymph nodes. Researchers are not sure what may cause inflammatory breast cancer.

Paget's disease of the breast is a rare form of breast cancer. It causes the skin around the nipple and areola to become scaly and thick, similar to eczema. This type of cancer usually forms in the tissue behind the nipple. Paget's disease of the breast is considered invasive cancer since it spreads to surrounding tissue.

Metastatic breast cancer, classified as Stage IV breast cancer, means that breast cancer has spread to other parts of the body, including the brain, liver, lungs, and bones. Metastatic breast cancer occurs when healthy breast tissue cells are invaded by cancer cells. They further replicate themselves into more abnormal cells. These abnormal cells enter the circulatory or lymph system causing cancer cells to travel to lymph or blood vessels. These cells are then carried to other parts of the body. The cancer cells cease traveling through the body and begin to infect the surrounding tissue.

HR+ breast cancer - Another way breast cancer is categorized is based on three receptors evaluated at diagnosis: ER, PR, and HER-2. A tumor contains hormone receptors, referred to as hormone receptor-positive or HR+. This means that the tumor needs estrogen and/or progesterone to grow. Approximately 80% of breast cancer cases are HR+. If a tumor does not contain hormone receptors, it is called hormone receptor-negative or HR-.

HER2+ breast cancer - All breast cells contain HER2 proteins, receptors controlling how the cells grow and divide. If breast tissue has extra HER2 receptors (overexpression), these breast cells can multiply too quickly, resulting in uncontrolled cell growth leading to a tumor.

Triple-negative breast cancer – In this form of breast cancer, estrogen, progesterone, and the HER2/neu gene, are not present in the cancerous tumor. The cancer is may be treated with chemotherapy, immunotherapy, surgery, and radiation therapy. If caught and treated early, this type of cancer responds well to chemotherapy.