What is Lobular Carcinoma in Situ (LCIS)?

Merriam Webster defines carcinoma -: noun, a malignant tumor of epithelial origin; medical: a type of cancer. Lobular carcinoma in situ (LCIS), however, is a condition in which abnormal cells form in the milk glands, known as lobules, in the breast, but LCIS is not cancer. The “in situ” part of the term means “in its original place” so these cells rarely spread to other parts of the breast or body. Being diagnosed with lobular carcinoma in situ is a red flag or a marker for cancer. Once these cells are identified, the risk of developing breast cancer is increased from a lifetime risk of 12.5% for the average woman to somewhere between 21-40%.

One of the scarier aspects of LCIS is that there are often no symptoms, and it is frequently missed in mammograms. LCIS doesn’t cause tell-tale lumps, so it is very difficult to detect. Usually, diagnosis is inadvertently made when a biopsy is being done for something unrelated. Plus, LCIS is very similar to ductal carcinoma in situ, which is actual breast cancer. Additional testing and/or a second opinion confirming diagnosis is a good idea before committing to treatment.

Risk Factors for Lobular Carcinoma in Situ

While it is not clear what causes the cells in a lobule of a breast to develop genetic mutations, there are risk factors that have been identified. If any of the following apply, your chances of developing LCIS may be increased:
• A family history of breast cancer – having one or more close relatives diagnosed at some point with any type of cancer seems to uniformly increase risk and LCIS is no exception.
• Hormone replacement therapy during and after menopause – HRT, while beneficial in many ways, has been blamed for increased risk of heart disease, blood clots, stroke, dementia and a host of other issues. LCIS can be added to that list. Women who use hormone replacement therapy for more than three to five years have an increased risk of LCIS.
• Being a woman in her early 40s – while LCIS is not common, when it does occur, it is most likely to do so in pre-menopausal women in their early 40s. This may be changing, however, or detection is getting better, because it is increasingly being diagnosed in older women who have undergone menopause.


LCIS is not cancer, and most women diagnosed with LCIS will never develop cancer. This means the kind of treatment we associate with cancer, like surgery, radiation therapy and chemotherapy will not usually be necessary. Some women, especially those with a family history of breast cancer, may decide to use strategies to reduce the risk of breast cancer in the future, such as medications or a preventive surgery called a prophylactic mastectomy. These are not easy decisions, and there are no one-size-fits-all answers. Each case must be assessed individually.
In general, most doctors will recommend close monitoring, to include, breast self-exams, regular office visits and routine mammograms or other tests, such as MRIs. LCIS, when it does develop into cancer, does not usually do so in the near future but will most likely wait 10 to 15 years, depending on the individual. For this reason, especially, it is important that monitoring and awareness become a lifelong commitment.