Breast Cancer Types

When breast cancer is diagnosed, the doctor will immediately determine its type and stage of development.

Breast cancer is first categorized by whether or not it has spread to other systems of the body, and whether or not it has the potential to be invasive. Breast cancer is also classified by the types of cells that comprise the tumor.

“In Situ” Versus “Metastatic” Breast Cancer

Cancers can be classified as “in situ” or “metastatic” based on their stage of development. In situ breast cancer consists of a localized tumor, which can often be completely removed. At the in situ stage, the cancer is described as non-invasive or pre-malignant. The in situ condition is sometimes referred to as “Stage 0” because it has not yet spread.

The majority of breast cancers, however, have already begun to spread (metastasize) by the time they are detected. When breast cancer is referred to as “metastatic,” it means that breast cancer cells have spread to other parts of the body.

Cancer that has metastasized from another part of the body to the breast is referred to by the original organ: Lung cancer that has spread to the breast is “lung cancer with metastasis to the breast,” or “secondary lung cancer.”

Cancer cells that spread are classified as “invasive.” Cancerous cells in the breast commonly spread to the lymph nodes and armpit area. From there, it’s possible for cancerous cells to metastasize throughout the body.


According to the American Cancer Society (2009), at least 95 percent of all breast cancers are carcinomas. Breast carcinomas are cancers that develop in the duct or lobular tissue of the breast. These cancers begin in situ, but have usually become invasive by the time breast cancer symptoms are noticed.

There are two types of carcinoma of the breast:

  • Ductal carcinomas, which are vastly more dangerous than lobular carcinomas. This type of breast cancer has the potential to spread quickly.
  • Lobular carcinomas, which tend to remain in situ and can usually be cured with a simple lumpectomy.

A woman who has had a lobular carcinoma is considered to be at a higher risk of developing ductal breast cancer in the future.

Sarcomas and Inflammatory Breast Cancer

A breast sarcoma is a malignant tumor that develops in the fatty or connective tissue of the mammary gland. A sarcoma, meaning “fleshy growth,” may or may not metastasize. According to the British Journal of Cancer (2004), less than 1 percent of all breast malignancies are sarcomas.

Inflammatory breast cancer (IBC) is an extremely aggressive type of cancer that comprises 1 to 5 percent of all breast malignancies, according to the National Cancer Institute (2006). In cases of IBC, the cancer cells block lymph vessels in the skin of the breast, giving the entire breast a red, swollen appearance–hence the term “inflammatory.”


American Cancer Society. (2009). Breast cancer facts and figures 2009-2010. Retrieved on October 22, 2010 from

British Journal of Cancer. (2004). Primary breast sarcoma: clinicopathologic series from the Mayo Clinic and review of the literature. Retrieved on October 25, 2010 from

National Cancer Institute. (2006). Inflammatory breast cancer: Questions and answers. Retrieved on October 25, 2010 from