This information is about lobular carcinoma in situ (LCIS). It should ideally be read with our general information about breast cancer.

Lobular carcinoma in situ (LCIS) is not a cancer, but its presence means that there is a small increase in the risk of developing breast cancer later in life. Even so, most women with LCIS do not develop breast cancer.

Each breast contains hundreds of tiny lobules where milk is produced before and after childbirth. With LCIS, changes are found in the cells in the lining of the lobules or lobes of the breast. It is often present in both breasts. LCIS is more common in women who have not reached their menopause (change of life).

LCIS does not show up on a mammogram (breast x-ray). It is usually discovered as a chance finding, when a sample of breast tissue is taken and examined under a microscope (biopsy), or when a breast lump is removed.

In the past, LCIS was often treated with surgery to remove the breast (mastectomy). This is now thought to be unnecessary, and women do not usually need any treatment when LCIS is diagnosed. Because most women with LCIS will not develop breast cancer, some will never need treatment.

Doctors now usually recommend that women with LCIS have breast examinations every 6–12 months, and mammograms every 1–2 years. Any changes in the breast can then be picked up at the earliest stage and treated if appropriate.

Rarely, a woman with LCIS may decide to have both breasts removed (bilateral mastectomy). This tends to happen where there is a strong family history of breast cancer, or the woman is extremely anxious about her risk of developing breast cancer.

A study called the International Breast Cancer Intervention Study (IBIS), which included women with LCIS, has shown that a hormonal therapy drug called tamoxifen may reduce the risk of LCIS developing into breast cancer in women who have had their menopause.

A second research trial, known as IBIS2, is being carried out to see whether another type of hormonal therapy, called anastrozole (Arimidex®), can also reduce the risk of breast cancer developing in post-menopausal women who have an increased risk. This trial includes women with LCIS.

Research into treatments for LCIS is ongoing, and advances are being made. Cancer doctors use clinical trials to assess new treatments. Before any trial is allowed to take place, an ethics committee must have approved it and agreed that the trial is in the interest of patients.

You may be asked to take part in a clinical trial. Your doctor must discuss the treatment with you so that you have a full understanding of the trial and what it involves. You may decide not to take part, or withdraw from a trial at any stage.

You may experience many different emotions, including anger, resentment, guilt, anxiety and fear. These are all normal reactions, and are part of the process many people go through in trying to come to terms with their illness.

This section has been compiled using information from a number of reliable sources, including:

• Cancer and Its Management (5th edition). Souhami and Tobias, Oxford Blackwell Scientific Publications, 2005
• Diseases of the Breast (2nd edition). Eds Harris et al. Lippincott Raven, 2000
• Improving Outcomes in Breast Cancer – The Research Evidence. National Institute of Clinical Excellence, 2002.

For further references, please see the general bibliography.