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Learning about breast cancer: Library

Parts of the breast Parts of the breast
  • Chest wall
  • Muscle
  • Lobules
  • Nipple
  • Areola
  • Duct
  • Fat
  • Lymph
    nodes
  • Blood
    vessels

What is breast cancer?

Breast cancer is cancer that forms in the breast. Normally, cells in our body divide and grow to replace old cells that have died. Sometimes, though, cells divide and grow out of control. This leads to too many cells. The extra cells then collect in a part of the body and form a tumor. Breast cancer is a tumor that starts in the cells in the breast.

Breast cancer happens most often in the ducts (the tubes that carry milk to the nipple) and the lobules (the glands that make the milk). Metastatic breast cancer is cancer that has spread from the breast to other parts of the body, such as the bones. Breast cancer that has spread to other parts of the body, such as the lungs, is still called breast cancer, not lung cancer.

To the right are examples of organizations and resources you may find helpful. Click on the links to visit those websites and learn more.


How common is breast cancer?

Breast cancer can happen to both men and women. In 2013, it was expected that more than 230,000 women and more than 2,200 men in the United States would be diagnosed with breast cancer. Ask your healthcare provider about your breast cancer risk.

To the right are examples of organizations and resources you may find helpful. Click on the links to visit those websites and learn more.


What are the different breast cancer types?

There are many types of breast cancer. Some types of breast cancer are very rare. Sometimes a breast tumor is made up of several types.

Some hormones, such as estrogen and progesterone, help breast cancers grow. Doctors and healthcare providers look at the status of these hormones, as well as at the status of a protein called human epidermal growth factor receptor type 2, or HER2, when they make treatment decisions for people with breast cancer.

To the right are examples of organizations and resources you may find helpful. Click on the links to visit those websites and learn more.


What is ER-positive and ER-negative breast cancer?

If a breast tumor is estrogen receptor (ER) positive or progesterone receptor (PR) positive, one or both of those hormones may be causing the tumor to grow. Breast cancers that are ER positive, PR positive, or both tend to stop growing or grow more slowly when a woman is treated with medicines that lower her estrogen levels or block estrogen from promoting the growth of breast cells.

To the right are examples of organizations and resources you may find helpful. Click on the links to visit those websites and learn more.


What is HER2-positive breast cancer?

HER2-positive (HER2+) breast cancer is a type of breast cancer that has high levels of a kind of protein called human epidermal growth factor receptor type 2 (known as HER2). High levels of the HER2 protein are caused by having too many copies of the HER2 gene.

HER2 protein tells cells to grow and divide. Having too much HER2 protein can cause breast cancer cells to grow and spread quickly. Researchers have found that women with HER2-positive breast cancer have more aggressive disease than women with HER2-negative breast cancer.

About 1 in 4 breast cancers is HER2 positive. Your doctor or healthcare provider can tell you if your breast cancer is HER2 positive. This information can also be found on your pathology report. Ask your doctor or healthcare provider for a copy of your pathology report so that you can review the results together.

If your breast cancer is HER2 positive, your doctor or healthcare provider may decide on a treatment specifically designed to target HER2-positive tumors.

To the right are examples of organizations and resources you may find helpful. Click on the links to visit those websites and learn more.

HER2-normal breast cancer cell HER2-normal breast cancer cell HER2-normal breast cancer cell
  • HER2 receptors send signals telling cells to grow and divide
  • Signal
  • Nucleus
HER2+ breast cancer cell HER2+ Breast cancer cell HER2+ Breast cancer cell
  • Too many HER2 receptors send more signals, causing cells to grow too quickly

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