Lobular Carcinoma in Situ (LCIS)

Lobular carcinoma in situ (LCIS) may also be called lobular neoplasia. In this breast change, cells that look like cancer cells are growing in the milk-producing glands of the breast (called the lobules), but they don’t grow through the wall of the lobules.

LCIS typically does not spread beyond the lobule (become invasive breast cancer) if it isn’t treated. But having LCIS increases your risk of developing an invasive breast cancer in either breast later on, so close follow-up is very important.

Diagnosis

LCIS is diagnosed by a biopsy. (Breast tissue is removed and checked under a microscope.) Often, LCIS does not cause a tumor that can be felt or changes that can be seen on a mammogram.¹ In most cases, LCIS is found when a biopsy is done for another breast problem that’s nearby.

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

Treatment

In most cases, LCIS does not need to be treated. 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 thing there. This is especially true if the LCIS is described as pleomorphic or if it has necrosis (areas of dead cells), in which case it might be more likely to grow quickly .

Women with LCIS are at higher risk for breast cancer, so close follow-up with a health care provider is very important. This usually includes yearly mammograms and breast exams. Close follow-up of both breasts is important because women with LCIS have the same increased risk of developing cancer in both breasts. There isn’t enough evidence to recommend routine breast MRI in addition to mammograms for all women with LCIS, but it’s reasonable for women with LCIS to talk with their doctors about their other risk factors and the benefits and limits of being screened yearly with MRI.

Women should also talk to a health care provider about what they can do to help reduce their breast cancer risk.

Some women with LCIS choose to take medicine to help lower their risk of breast cancer. More details on this can be found in Deciding Whether to Use Medicine to Reduce Breast Cancer Risk.

Because LCIS is linked to an increased risk of cancer in both breasts, some higher risk women with LCIS (such as those with a strong family history of breast cancer or certain genetic changes) choose to have a bilateral prophylactic mastectomy (removal of both breasts but not lymph nodes) to help lower this risk. This may be followed by delayed breast reconstruction. 

How does LCIS affect breast cancer risk?

Women with LCIS have a 7 to 11 times higher risk of developing invasive cancer in either breast.² For this reason, women with LCIS should make sure they have regular breast cancer screening tests and follow-up visits with a health care provider for the rest of their lives.