Types of Breast Cancer

There are many types of breast cancer, and many different ways to describe them. It’s easy to get confused over a breast cancer diagnosis.

The type of breast cancer is determined by the specific cells in the breast that are affected. 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 (milk-producing glands).

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 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 affect 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 affect other types of cells in the breast. These cancers are much less common, and sometimes need different types of treatment.

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 journalists, editors, and translators with extensive experience in medical writing.

Anders CK and Carey LA. ER/PR negative, HER2-negative (triple-negative) breast cancer. UpToDate website. https://www.uptodate.com/contents/er-pr-negative-her2-negative-triple-negative-breast-cancer. Updated June 06, 2019. Accessed July 23, 2019. 

Calhoun KE, Allison KH, Kim JN et al. Chapter 62: Phyllodes Tumors.  In: Harris JR, Lippman ME, Morrow M, Osborne CK, eds. Diseases of the Breast. 5th ed. Philadelphia, Pa: Lippincott-Williams & Wilkins; 2014.

Dillon DA, Guidi AJ, Schnitt SJ. Ch. 25: Pathology of invasive breast cancer. In: Harris JR, Lippman ME, Morrow M, Osborne CK, eds. Diseases of the Breast. 5th ed. Philadelphia, Pa: Lippincott-Williams & Wilkins; 2014.

Esteva FJ and Gutiérrez C. Chapter 64: Nonepithelial Malignancies of the Breast. In: Harris JR, Lippman ME, Morrow M, Osborne CK, eds. Diseases of the Breast. 5th ed. Philadelphia, Pa: Lippincott-Williams & Wilkins; 2014.

Henry NL, Shah PD, Haider I, Freer PE, Jagsi R, Sabel MS. Chapter 88: Cancer of the Breast. In: Niederhuber JE, Armitage JO, Doroshow JH, Kastan MB, Tepper JE, eds. Abeloff’s Clinical Oncology. 6th ed. Philadelphia, Pa: Elsevier; 2020.

Jagsi R, King TA, Lehman C, Morrow M, Harris JR, Burstein HJ. Chapter 79: Malignant Tumors of the Breast. In: DeVita VT, Lawrence TS, Lawrence TS, Rosenberg SA, eds. DeVita, Hellman, and Rosenberg’s Cancer: Principles and Practice of Oncology. 11th ed. Philadelphia, Pa: Lippincott Williams & Wilkins; 2019.

National Comprehensive Cancer Network (NCCN). Practice Guidelines in Oncology: Breast Cancer. Version 2.2019. Accessed at https://www.nccn.org/professionals/physician_gls/pdf/breast.pdf on July 23, 2019.

Nora M. Hansen. Chapter 63: Paget's Disease. In: Harris JR, Lippman ME, Morrow M, Osborne CK, eds. Diseases of the Breast. 5th ed. Philadelphia, Pa: Lippincott-Williams & Wilkins; 2014.

Overmoyer B and Pierce LJ. Chapter 59: Inflammatory Breast Cancer. In: Harris JR, Lippman ME, Morrow M, Osborne CK, eds. Diseases of the Breast. 5th ed. Philadelphia, Pa: Lippincott-Williams & Wilkins; 2014.

Last Medical Review: September 20, 2019 Last Revised: September 20, 2019

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