Types of Breast Cancer
There are many types of breast cancer, and many different ways to describe them. It’s easy to get confused.
A breast cancer's type is determined by the specific cells in the breast that become cancer.
Ductal or lobular carcinoma
Most breast cancers are carcinomas, which are tumors that start in the epithelial cells that line organs and tissues throughout the body. When carcinomas form in the breast, they are usually a more specific type called adenocarcinoma, which starts in cells in the ducts (the milk ducts) or the lobules (glands in the breast that make milk).
In situ vs. invasive breast cancers
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 pre-cancer that starts in a milk duct and has not grown into the rest of the breast tissue. 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.
Special types of invasive breast cancers
Some invasive breast cancers have special features or develop in different ways that influence their treatment and outlook. These cancers are less common but can be more serious than other types of breast cancer.
Less common types of breast cancer
There are other types of breast cancers that start to grow in other types of cells in the breast. These cancers are much less common, and sometimes need different types of treatment.
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The American Cancer Society medical and editorial content team
Our team is made up of doctors and oncology certified nurses with deep knowledge of cancer care as well as editors and translators with extensive experience in medical writing.
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Last Revised: November 19, 2021
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