Learn about breast cancer categories and subtypes
Learn about breast cancer categories and subtypes

Breast Cancer 101 

During October, pink ribbons are a common sight, and you probably know someone who has had breast cancer. But do you really understand as much about breast cancer as you think you do? 

For example, did you know that one in eight U.S. women will develop invasive breast cancer over the course of her lifetime? In recent years, there’s been an explosion of life-saving treatment advances against breast cancer, bringing new hope to patients who are diagnosed with this disease. 
“At UAMS, we understand that every woman is unique, so each of our patients receives personalized medicine, working with our Breast Team to determine the best treatment plan,” said Dr. Ronda Henry-Tillman, Director of Breast Surgical Oncology. “Our Breast Team consists of dedicated and compassionate experts committed to our patients while ensuring superior cancer treatment.”

    What is Cancer?

    Cancer is when cells in the body change and grow out of control. Your body is made up of tiny building blocks called cells. Normal cells grow when your body needs them, and die when your body does not need them any longer. Cancer is made up of abnormal cells that grow even though your body doesn’t need them. In most types of cancer, the abnormal cells grow to form a lump or mass called a tumor.

    Understanding the Breast

    The breast is made up of lobules and ducts. The lobules are the glands that can make milk. The ducts are thin tubes that carry the milk from the lobules to the nipple. The breast is also made of fat, connective tissue, lymph nodes and blood vessels.

    What is Breast Cancer?

    Breast cancer is cancer that starts in the breast. It occurs when cells in the breast are changed and start to grow out of control. The ducts and the lobules are the two parts of the breast where cancer is most likely to occur. 
    Breast cancer is one of the most common types of cancer in women in the U.S. Doctors don't yet know exactly what causes it. Once breast cancer occurs, cancer cells can spread to other parts of the body, making it life-threatening. The good news is that breast cancer is often found early, before it has spread.

    Categories of Breast Cancer

    Noninvasive (in situ) cancer. This occurs only in the ducts or lobules and doesn’t spread to nearby areas. If not treated, it can later grow into a more serious, invasive type of cancer. If you are diagnosed with noninvasive carcinoma, your chances of surviving are very high if you don’t wait to treat it. If you do wait, you’re at risk of the cancer becoming invasive. Invasive cancer is harder to treat.
    Types of Noninvasive Cancer
    • Ductal Carcinoma in situ (DCIS). Cancer starts inside the milk ducts.
    • Lobular Carcinoma in situ (LCIS). A marker for the risk of breast cancer.
    Invasive (infiltrating) cancer. This kind of cancer has started to spread to nearby areas. This type is much more serious than noninvasive cancer. It often invades nearby lymph nodes first. It can then spread to other parts of your body through your bloodstream and lymphatic system. Treatment for invasive cancer is usually a more difficult, long-term process.
    Subtypes of Invasive Breast Cancer
    • Invasive Ductal Carcinoma. Cancer has spread to surrounding breast tissues. Most common form of invasive breast cancer.
    • Tubular Carcinoma of the Breast
    • Medullary Carcinoma of the Breast
    • Mucinous Carcinoma of the Breast
    • Papillary Carcinoma of the Breast
    • Cribriform Carcinoma of the Breast
    • Inflammatory Breast Cancer. A rare and aggressive form of breast cancer that usually starts with the reddening and swelling of the breast instead of a distinct lump.
    • Invasive Lobular Carcinoma. Cancer that beings in the milk-carrying ducts and spreads beyond it.
    Additional Types of Cancer
    • Male Breast Cancer. The lifetime risk of a male being diagnosed with breast cancer is about 1 in 1,000. Usually invasive at the time of diagnosis.
    • Paget’s Disease of the Nipple. Cancer cells collect in or around the nipple. May be associated with in situ or invasive cancer.
    • Phyllodes Tumors of the Breast. Tumor cells grow in a leaf-like pattern. Although most phyllodes tumors are benign (noncancerous), some are malignant (cancerous) and some are borderline (in between noncancerous and cancerous).
    • Metastatic Breast Cancer. Breast cancer that has spread to other parts of the body such as the bones, liver, lungs, or brain.

    Breast Cancer Molecular Subtypes:
    (Breast cancers can be described by subtypes)

    • Her2-Positive. Breast cancer that test positive for the protein human growth factor receptor 2 (HER2), which promotes the growth of cancer cells.
    • Luminal A. A high expression of hormone receptors (estrogen receptor) and progesterone receptor, and low expression of the cell-growth marker KI67 and the HER2.
    • Luminal B. Estrogen receptor positive and is defined by the increased proliferation, relative resistance to chemotherapy compared with other highly proliferative breast cancers.
    • Triple negative breast cancer. This cancer does not express the genes for estrogen receptor, progesterone receptor, or HER2.

    How Breast Cancer Spreads

    Breast cancer can spread by growing into nearby tissues in the breast or when the cancer cells get into and travel through the blood or lymph systems. When this happens, cancer cells may be found in the lymph nodes in the armpit. These lymph nodes are called axillary lymph nodes. They are often checked for cancer as part of the diagnosis process. If the cancer reaches these nodes, it may have spread to other parts of the body.

    Breast cancer that has spread to other organs of the body is called metastatic breast cancer. When breast cancer spreads to other parts of the body, it most often goes to the brain, bones, liver, or lungs.
    To learn more, visit the UAMS Health Library
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