Lobes, Lobules and Breast Cancer

Each breast is composed of up to 20 sections called "lobes." Each lobe is made up of many smaller "lobules," where milk is made. Lobes and lobules are connected by small tubes called "ducts" that can carry milk to the nipple.

Lobular carcinoma in situ (LCIS) is a benign tumor that consists of abnormal cells in the lining of a lobule. Even though "carcinoma" refers to cancer, LCIS is not a cancer and there is no evidence that the abnormal cells of LCIS will spread like cancer. Instead, having LCIS means that a woman has an increased risk of developing breast cancer in either breast. Despite the increased risk, most women with LCIS will never get breast cancer. No treatment is necessary and surgery is not usually recommended for LCIS. Occasionally women with LCIS choose bilateral mastectomy as a preventive measure, but most surgeons consider this inappropriate. Some women choose to take tamoxifen to decrease the likelihood of breast cancer. LCIS is sometimes called "Stage 0" breast cancer, but that is not really accurate because it is not really cancer.

Ductal carcinoma in situ (DCIS) is made up of abnormal cells in the lining of a duct. It is a non-invasive malignant tumor, and is also called intraductal carcinoma. The abnormal cells have not spread beyond the duct and have not invaded the surrounding breast tissue. However, DCIS can progress and become invasive. There is no official recommended surgical treatment for DCIS, although a national Consensus Conference held in Philadelphia in 1999 concluded that "most women with DCIS" are eligible for breast-conserving surgery and that less than one in four require mastectomy. The addition of radiation therapy helps prevent recurrence of DCIS and the development of invasive breast cancer. If the DCIS is spread out or is in more than one location, some women will choose to undergo a mastectomy. In the treatment of DCIS, underarm lymph nodes usually are not removed with either breast-conserving surgery or mastectomy. Tamoxifen is sometimes used in combination with one of these two surgical treatment options.

DCIS is sometimes called Stage 0 breast cancer because it is not invasive.