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. Carcinoma refers to any cancer that begins in the skin or other tissues that cover internal organs — such as breast tissue. In situ or “in its original place” means that the abnormal growth remains inside the lobule and does not spread to surrounding tissues. People diagnosed with LCIS tend to have more than one lobule affected.
Despite the fact that its name includes the term “carcinoma,” LCIS is not a true breast cancer. Rather, LCIS is an indication that a person is at higher-than-average risk for getting breast cancer at some point in the future. For this reason, some experts prefer the term “lobular neoplasia” instead of “lobular carcinoma.” A neoplasia is a collection of abnormal cells.
LCIS is usually diagnosed before menopause, most often between the ages of 40 and 50. Less than 10% of women diagnosed with LCIS have already gone through menopause. LCIS is extremely uncommon in men.
LCIS is viewed as an uncommon condition, but we don’t know exactly how many people are affected. That’s because LCIS does not cause symptoms and usually does not show up on a mammogram. It tends to be diagnosed as a result of a biopsy performed on the breast for some other reason.
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