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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.
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.
The breasts contain ducts, which are thin tubes that carry milk toward the nipple, and lobules, small sacs where milk is made. Breast cancer can develop from the cells that line either one.
Doctors group breast carcinomas into 2 main types, ductal and lobular, based on how the cancer cells look and grow under a microscope.
- Ductal carcinomas form solid clusters or tubes of cells, similar to the shape of a duct.
- Lobular carcinomas grow in single-file lines or spread out, rather than forming a cluster. This happens because the cancer cells lose a protein that normally holds cells together.
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.
Less common types of invasive breast cancer
Other less common types of breast cancer are typically named after features of the cancer cells, such as the way the cells are arranged.
Some tend to have a better prognosis (outlook) than the more common IDC:
- Adenoid cystic carcinoma (adenocystic carcinoma)
- Cribriform carcinoma
- Low-grade adenosquamous carcinoma (a type of metaplastic carcinoma)
- Medullary carcinoma
- Mucinous carcinoma (colloid carcinoma)
- Tubular carcinoma
Some types tend to have the same or possibly a worse outlook than IDC. These include:
- Metaplastic carcinoma (most types, including spindle cell and squamous, except for low-grade adenosquamous carcinoma)
- Micropapillary carcinoma
- Mixed carcinoma (cancers that have features of both IDC and ILC)
- Tubulolobular carcinoma
Breast cancers with specific features
Some types of invasive breast cancer have special features or develop in different ways, which can influence their treatment and outlook.
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.
Other cancers that rarely start in the breast include soft tissue sarcomas and some types of non-Hodgkin lymphomas.
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- References
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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Last Revised: August 26, 2026
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