Lobular Carcinoma in Situ (LCIS)

Lobular carcinoma in situ (LCIS) is a type of breast change that is sometimes seen when a breast biopsy is done. In LCIS, cells that look like cancer cells are growing in the lining of the milk-producing glands (lobules) of the breast, but they don’t invade through the wall of the lobules.

LCIS is not considered cancer, and it typically does not spread beyond the lobule (that is, it doesn't become invasive breast cancer) if it isn’t treated. But having LCIS does increase your risk of later developing an invasive breast cancer in either breast. (See "How does LCIS affect breast cancer risk?")

LCIS and another type of breast change (atypical lobular hyperplasia, or ALH) are types of lobular neoplasia. These are benign (non-cancerous) conditions, but they both increase your risk of breast cancer.

The different types of LCIS are:

• Classic LCIS: The cells lining the lobules of the breast are smaller and are about the same size.
• Pleomorphic LCIS: The cells lining the lobules of the breast are larger and look more abnormal.
• Florid LCIS: The cells lining the lobules have grown into a large enough group that they have formed a mass, typically with an area of dead cells in the middle (called central necrosis).

Diagnosis of LCIS

Classic LCIS usually doesn't cause a lump that can be felt or changes that can be seen on a mammogram, although pleomorphic and florid LCIS are sometimes found this way. Most often, LCIS is found when a breast biopsy is done for another problem that’s nearby. (During a biopsy, small pieces of breast tissue are removed and checked in the lab.)

You can learn more about pathology reports showing LCIS in Understanding Your Pathology Report: Lobular Carcinoma In Situ.

How does LCIS affect breast cancer risk?

Women with LCIS have about a 7 to 12 times higher risk of developing invasive cancer in either breast. For this reason, doctors typically recommend that women with LCIS have regular breast cancer screening tests and follow-up visits with a health care provider for the rest of their lives.

Treatment for LCIS

Having LCIS does increase your risk of developing invasive breast cancer later on. But since LCIS is not a true cancer or pre-cancer, often no treatment is needed after the biopsy.

Sometimes if LCIS is found using a needle biopsy, the doctor might recommend that it be removed completely (with an excisional biopsy or some other type of breast-conserving surgery) to help make sure that LCIS was the only abnormality there. This is especially true if the LCIS is described as pleomorphic or florid, in which case it might be more likely to grow quickly.

Even after an excisional biopsy, if pleomorphic or florid LCIS is found, some doctors might recommend another, more extensive surgery to make sure it has all been removed.

Reducing breast cancer risk or finding it early

Close follow-up is important because women with LCIS have the same increased risk of developing cancer in both breasts. Women should also talk to a health care provider about what they can do to help reduce their breast cancer risk. Options for women at high risk of breast cancer because of LCIS may include:

• Seeing a health care provider more often (such as every 6 to 12 months) for a breast exam along with the yearly mammogram. Additional imaging with breast MRI may also be recommended, especially if a woman has other factors that raise her risk of breast cancer.
• Making lifestyle changes to lower breast cancer risk. To learn more, see Can I Lower My Risk of Breast Cancer?  
• Taking medicine to help lower the risk of breast cancer. For more on this, see Deciding Whether to Use Medicine to Reduce Breast Cancer Risk.
• Surgery, called bilateral prophylactic mastectomy (removal of both breasts), to reduce risk. (This is more likely to be a reasonable option in women who also have other risk factors for breast cancer, such as a BRCA gene mutation.)  This may be followed later by breast reconstruction.