Types of Breast Cancer
The most common types of breast cancer are ductal carcinoma in situ, invasive ductal carcinoma, and invasive lobular carcinoma.
How type is determined
Most breast cancers are carcinomas. These cancers start in the cells that line organs and tissues. (These cells are called epithelial cells.) In fact, breast cancers are often a type of carcinoma called adenocarcinoma, which starts in cells that make glands (glandular tissue). Breast adenocarcinomas start in the ducts (the milk ducts) or the lobules (milk-producing glands).
There are other types of breast cancers, too, such as sarcomas, which start in the cells of the muscle, fat, or connective tissue.
Sometimes a single breast tumor can be a combination of different types. And in some very rare types of breast cancer, the cancer cells may not form a lump or tumor at all.
Doctors will try to find out whether the cancer has spread beyond the place it started.
- In situ breast cancers have not spread.
- Invasive or infiltrating cancers have spread (invaded) into the surrounding breast tissue.
Common kinds of breast cancer
These general kinds of breast cancer can be further described with the terms outlined above.
Ductal carcinoma in situ
Ductal carcinoma in situ (DCIS; also known as intraductal carcinoma) is a non-invasive or pre-invasive breast cancer.
Lobular carcinoma in situ
Lobular carcinoma in situ (LCIS) may also be called lobular neoplasia. This breast change is not a cancer, though the name can be confusing. In LCIS, cells that look like cancer cells are growing in the lobules of the milk-producing glands of the breast, but they don’t grow through the wall of the lobules.
Invasive (or infiltrating) ductal carcinoma
This is the most common type of breast cancer. Invasive (or infiltrating) ductal carcinoma (IDC) starts in a milk duct of the breast, breaks through the wall of the duct, and grows into the fatty tissue of the breast.
Invasive (or infiltrating) lobular carcinoma
Invasive lobular carcinoma (ILC) starts in the milk-producing glands (lobules). Like IDC, it can spread to other parts of the body.
Special types of invasive breast carcinoma
There are some special types of breast cancer that are sub-types of invasive carcinoma. These are often named after features seen when they are viewed under the microscope, like the ways the cells are arranged.
Some of these may have a better prognosis than standard infiltrating ductal carcinoma. These include:
- Adenoid cystic (or adenocystic) carcinoma
- Low-grade adenosquamous carcinoma (this is a type of metaplastic carcinoma)
- Medullary carcinoma
- Mucinous (or colloid) carcinoma
- Papillary carcinoma
- Tubular carcinoma
Some sub-types have the same or maybe worse prognoses than standard infiltrating ductal carcinoma. These include:
- Metaplastic carcinoma (most types, including spindle cell and squamous)
- Micropapillary carcinoma
- Mixed carcinoma (has features of both invasive ductal and lobular)
In general, all of these sub-types are still treated like standard infiltrating
Less common types of breast cancer
Inflammatory breast cancer
Inflammatory breast cancer is an uncommon type of invasive breast cancer. It accounts for about 1% to 3% of all breast cancers.
Paget disease of the nipple
This type of breast cancer starts in the breast ducts and spreads to the skin of the nipple and then to the areola, the dark circle around the nipple. It is rare, accounting for only about 1% of all cases of breast cancer.
Phyllodes tumors are rare breast tumors. They develop in the connective tissue (stroma) of the breast, in contrast to carcinomas, which develop in the ducts or lobules.
This form of cancer rarely occurs in the breasts. Angiosarcoma starts in cells that line blood vessels or lymph vessels.
Dillon DA, Guidi AJ, Schnitt SJ. Pathology of invasive breast cancer. In: Harris JR, Lippman ME, Morrow M, Osborne CK, eds. Diseases of the Breast. 4th ed. Philadelphia, Pa: Lippincott-Williams & Wilkins; 2010: 374−407.
Last Medical Review: June 1, 2016 Last Revised: August 18, 2016