Breast Cancer

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Types of Breast Cancer

A breast cancer's type is determined by the specific cells in the breast that become cancer. There are many types of breast cancer and different ways to describe them.

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Ductal and lobular carcinoma

Most breast cancers are carcinomas, which are cancers that start in the epithelial cells that line organs and tissues throughout the body. Most of these are a type of carcinoma that starts in glandular tissue, which is called an adenocarcinoma.  

Most breast cancers start either in milk ducts (tiny tubes) or in groups of sacs called lobules, where milk is made.

  • Ductal carcinomas are cancers that start in duct cells.
  • Lobular carcinomas are cancers that start in lobular cells.

color illustration showing the structure of the breast (including location of areola, nipple, collecting ducts, ducts, lobules, fatty connective tissue, duct cells and lobular cells)

In situ vs. invasive breast cancer

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

  • In situ breast cancer, also called carcinoma in situ or CIS, grows within the lining layer of cells where it started, but it isn’t growing into (invading) deeper layers of the breast.
  • Invasive (or infiltrating) breast cancer describes any type of breast cancer that has invaded deeper layers of breast tissue.

Ductal carcinoma in situ (DCIS)

Ductal carcinoma in situ (DCIS; also known as intraductal carcinoma) is a non-invasive or pre-invasive breast cancer. 
Invasive breast cancer (ILC or IDC)

Invasive (or infiltrating) breast cancer has spread into surrounding breast tissue. The most common types are invasive ductal carcinoma and invasive lobular carcinoma. Invasive ductal carcinoma makes up about 70-80% of all breast cancers. 

Less common types of invasive breast cancer

Some less common types of invasive breast cancer have special features or develop in different ways, which can influence their treatment and outlook.

Triple-negative breast cancer

Triple-negative breast cancer is an aggressive type of invasive breast cancer in which the cancer cells don’t have estrogen or progesterone receptors (ER or PR) and also don’t make any or too much of the protein called HER2. (The cells test "negative" on all 3 tests.) It accounts for about 15% of all breast cancers and can be a difficult cancer to treat.
Inflammatory breast cancer

Inflammatory breast cancer is an aggressive type of invasive breast cancer in which cancer cells block lymph vessels in the skin, causing the breast to look "inflamed." It is rare and accounts for about 1% to 5% of all breast cancers.
Paget disease of the breast

Paget disease of the breast is rare, accounting for only about 1-3% of all cases of breast cancer.  It starts in the breast ducts and spreads to the skin of the nipple and then to the areola (the dark circle around the nipple). 

Breast sarcomas and lymphomas

Breast sarcomas start to grow in cells besides the breast ducts and lobules. These cancers are much less common, and sometimes need different types of treatment.

Angiosarcoma

Sarcomas of the breast are rare making up less than 1% of all breast cancers. Angiosarcoma starts in cells that line blood vessels or lymph vessels. It can involve the breast tissue or the skin of the breast. Some may be related to prior radiation therapy in that area. 

Other cancers that rarely start in the breast include soft tissue sarcomas and some types of non-Hodgkin lymphomas.

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Developed by the American Cancer Society medical and editorial content team with medical review and contribution by the American Society of Clinical Oncology (ASCO).

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National Comprehensive Cancer Network. NCCN Clinical Practice Guidelines in Oncology: Breast Cancer. Version 2.2026. Accessed at https://www.nccn.org on March 31, 2026.

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Last Revised: June 24, 2026

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