Types of Breast Cancer

If breast cancer is diagnosed after a biopsy, additional tests may be recommended to determine the optimal treatment. There are many different types of breast cancer, and treatment recommendations may vary based on the specific breast cancer subtype and cancer stage. Breast tissue is made up of both lobules (where milk is produced) and ducts (which carry milk to the nipple), and cancers can arise from either. Cancers that begin in other tissues in the breast are much more rare.

Ductal Carcinoma in Situ (DCIS)

Ductal carcinoma in situ (DCIS), also called intraductal carcinoma, refers to cancer cells contained within the lining of the milk ducts. In DCIS, cancer cells have not spread beyond the ducts to invade the surrounding breast tissue, and therefore, the risk of spread of cancer to lymph nodes and elsewhere in the body is much lower than with invasive breast cancer. However, women with DCIS are at increased risk of getting invasive breast cancer in the future, and DCIS can be found adjacent to areas of invasive breast cancer. If DCIS alone is found at surgery, this is classified as Stage 0 breast cancer. Treatment of DCIS can include surgery and radiation therapy.

Lobular Carcinoma in Situ (LCIS)

Lobular carcinoma in situ (LCIS) refers to abnormal cells in the lining of a lobule. These abnormal cells are not considered to be breast cancer and do not require any treatment beyond surgical removal. However, the presence of LCIS is a marker of increased risk of developing breast cancer in either breast in the future, and more aggressive breast cancer screening or preventative measures (including taking medication such as tamoxifen or raloxifene) may be recommended.

Invasive Ductal Breast Cancer

Invasive ductal carcinoma is the most common type of breast cancer and refers to cancer cells that arise within the ducts that link the lobules to the nipple, and have moved through the lining of the ducts into the surrounding tissues where the blood and lymphatic vessels are located. Invasive ductal cancers can spread along the blood and lymphatic vessels to other parts of the body. Consequently, treatment of invasive ductal cancers requires surgical removal of the cancer in the breast, as well as some of the axillary (under arm) lymph nodes to determine the cancer stage. This can be done as either a sentinel lymph node biopsy or axillary lymph node dissection.

Invasive Lobular Breast Cancer

Invasive lobular carcinoma is the second most common type of breast cancer and refers to cancer cells that develop within the breast lobules. This cancer may be more difficult to diagnose because lobular cancers do not always present as lumps and may present as fullness in a particular area in the breast.

Inflammatory Breast Cancer

This rare but aggressive form of breast cancer arises when breast cancer cells block the lymphatic vessels in the skin of the breast. As a result, the breast may appear swollen, red, and inflamed, much like an infection. Inflammatory breast cancers do not tend to present as a mass; rather, they grow in sheets of cells in the lymphatics of the skin, making them difficult to detect in a physical exam. Any breast infection that does not resolve with antibiotic treatment should be evaluated further to exclude inflammatory breast cancer.

Paget's Disease of the Breast

Paget's disease of the breast, also called Paget's disease of the nipple, is a very rare type of breast cancer. It starts in or around the nipple in the areola (dark area of skin surrounding the nipple). Cancer cells within the skin of the nipple cause redness and mild scaling and flaking of the nipple skin and may resemble eczema, a non-cancerous skin condition. Most women with Paget's disease of the nipple also have either DCIS or invasive breast cancer elsewhere in the breast. Diagnosis is made with a biopsy of the skin of the nipple.