The Westport Library Resource Guides: Breast Cancer Awareness: About

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What is Breast Cancer?

Breast cancer is a cancer that starts in breast tissue. It happens when cells in the breast change and grow out of control. The cells usually form a tumor. Sometimes the cancer does not spread any further. This is called "in situ." If the cancer spreads outside the breast, the cancer is called "invasive." It may just spread to nearby tissues and lymph nodes. Or the cancer may metastasize (spread to other parts of the body) through the lymph system or the blood. Breast cancer is the second most common type of cancer in women in the United States. Rarely, it can also affect men.

There are different types of breast cancer. The types are based on which breast cells turn into cancer. The types include:

Ductal carcinoma, which begins in the cells of the ducts. This is the most common type.
Lobular carcinoma, which begins in the lobules. It is more often found in both breasts than other types of breast cancer.
Inflammatory breast cancer, in which cancer cells block lymph vessels in the skin of the breast. The breast becomes warm, red, and swollen. This is a rare type.
Paget's disease of the breast, which is a cancer involving the skin of the nipple. It usually also affects the darker skin around the nipple. It is also rare. Continue reading from MedlinePlus