Lobular carcinoma in situ (LCIS) is an area (or areas) of abnormal cell growth that increases a person’s risk of developing invasive breast cancer later on in life. Lobular means that the abnormal cells start growing in the lobules, the milk-producing glands at the end of breast ducts.
What is lobular carcinoma in situ (LCIS)? The lobules of the breast are small round sacs that produce milk for breastfeeding. When abnormal cells grow inside the lobules, but have not spread to nearby tissue or beyond, the condition is called lobular carcinoma in situ (LCIS).
Lobular carcinoma in situ (LCIS) means abnormal cells are in the lobules of the breast. LCIS is sometimes grouped with ductal carcinoma in situ (DCIS) as a type of non-invasive breast cancer, but LCIS is different from DCIS and is not cancer. Most breast cancers start in the ducts of the breasts, but some begin in the glands that produce milk, called the lobules. LCIS isn’t cancer, but it’s thought to be a sign that breast cancer.
Tamoxifen works to reduce the risk of an invasive breast cancer from developing in the future. A large clinical trial called The Breast Cancer Prevention Trial found that women with LCIS who took tamoxifen for 5 years reduced their risk of invasive breast cancer by 46%.
Lobular carcinoma in situ (LCIS) is a noninvasive precancer located in the lobule, the parts of the breast capable of making milk Under the microscope, LCIS appears as a bunch of small, round cells stuffing the lobules, which normally don't contain any cells.