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Breast Cancer Resource
What Is Breast Cancer?

What Is Breast Cancer?

Breast cancer is a group of diseases in which cells in breast tissue change and divide uncontrolled, typically resulting in a lump or mass.

Most breast cancers begin in the lobules (milk glands) or in the ducts that connect the lobules to the nipple.

What are breasts?
Breasts are mostly made of a collection of fat cells (adipose tissue), lobes, lobules, and milk ducts. Each lobe is made up of smaller lobules, the gland that produces milk in nursing women. Both lobes and lobules are connected by milk ducts. Milk ducts carry the milk to the nipple.

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Stages of Breast Cancer

After someone is diagnosed with breast cancer, doctors will try to figure out if it has spread, and if so, how far. This process is called staging. The stage of a cancer describes how much cancer is in the body. It helps determine how serious the cancer is and how best to treat it.

Stage 0
Stage I
Stage II
Stage III
Stage IV

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Understanding How Breast Cancer Spreads

The type of breast cancer can also refer to whether the cancer has spread or not. 

In situ breast cancer (ductal carcinoma in situ or DCIS) is a cancer that starts in a milk duct and has not grown into the rest of the breast tissue. (DCIS also known as intraductal carcinoma) is a non-invasive or pre-invasive breast cancer. 

The term invasive (or infiltrating) breast cancer is used to describe any type of breast cancer that has spread (invaded) into the surrounding breast tissue.

According to the American Cancer Society 2020.

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