Lobular carcinoma in situ (LCIS) is an abnormal growth of cells in the lining of the milk-producing glands of the breast, which are called lobules.

While the cells look cancerous, LCIS does not invade the lobule walls or spread to other parts of the breast.

If a person with LCIS does not receive treatment for the condition, it usually does not grow beyond the lobule. For this reason, doctors do not consider it cancer.

However, after someone receives an LCIS diagnosis, their risk of developing breast cancer is 9 to 10 times higher than the general population.

LCIS is uncommon. Doctors find it in 0.5 to 1.5% of noncancerous breast biopsies and in 1.8 to 2.5% of all breast biopsies.

This article discusses the symptoms, causes, and diagnosis, as well as the treatment and prognosis, of LCIS. It also examines the differences between LCIS and other noninvasive breast cell growths.

A mammogram of a breast as part of a diagnosis of lobular carcinoma in situ.Share on Pinterest
Science Photo Library – MIRIAM MASLO/Getty Images

LCIS does not produce signs and symptoms such as lumps or changes in the appearance of the breast. It also may not show on a mammogram, partly because it often lacks the small calcium deposits that are sometimes characteristic of other types of breast cancer.

Doctors do not know the exact cause of LCIS, but studies suggest the risk factors are similar to those of breast cancer. A 2017 study compared risk factor associations between breast cancer and conditions that possibly lead to it, such as LCIS. It found a link between the use of hormone replacement therapy (HRT) for menopause and LCIS.

The authors of the study discovered that the risk factors for LCIS resemble those of breast cancer. This suggests most risk factors influence tumor formation early. Examples of these include:

  • a family history of breast cancer
  • smoking
  • excess alcohol consumption

Ductal carcinoma in situ (DCIS) involves abnormal cells in the milk ducts, which are tubes that transport milk to the nipples. LCIS and DCIS are two types of noninvasive breast growths. They do not invade other breast tissue.

LCIS is much less common than DCIS. According to a 2019 study, DCIS was responsible for 18–25% of newly diagnosed breast tumors in the United States between 2000 and 2014.

Of the two conditions, DCIS is more serious. Doctors consider DCIS precancer, but it is not clear if LCIS is definitely precancer or merely a risk factor for breast cancer development.

Doctors most often diagnose LCIS in people between the ages of 40 and 50. According to the American Cancer Society (ACS), since LCIS does not have any signs, doctors usually find it when they perform a biopsy for a nearby breast condition.

A biopsy involves removing a small piece of tissue and examining the cells in a lab.

Doctors may use one of two types of biopsies when examining breast tissue.

A needle biopsy uses a needle to remove a sample of an abnormal area.

An excision biopsy involves the removal of the entire abnormal area and frequently includes surrounding healthy tissue.

Treatment depends on whether LCIS is found in a needle or an excision biopsy.

Needle biopsy

Doctors are uncertain of the best way to treat LCIS found in a needle biopsy. One option involves removing the entire area of abnormal cells with an excision biopsy. This is similar to a lumpectomy, a surgery that removes cancerous breast tissue along with a rim of healthy surrounding tissue.

Doctors may opt for this step if one of two things applies. In the first case, the LCIS cells look pleomorphic. This means that the cells appear more abnormal under a microscope than typical LCIS.

In the second case, the LCIS has necrosis. A necrotic LCIS indicates some of the cells are dead.

Excisional biopsy

An LCIS found with an excision biopsy does not need further treatment. However, if the LCIS looks pleomorphic, some doctors may recommend another surgery to ensure the removal of all the abnormal cells. This step is a precaution because pleomorphic LCIS has a higher likelihood of developing into cancer.

Because people with LCIS have a higher risk of breast cancer, they may consider taking steps to decrease their risk or increase the chance of early detection. These include:

Seeing a doctor more frequently

In addition to a yearly mammogram, a doctor may recommend a breast exam every 6–12 months.


Doctors sometimes recommend taking medications to lower the risk of developing breast cancer. The goal of these drugs is to reduce a person’s exposure to estrogen, which fuels cancer growth.

The most common drugs doctors use for prevention are tamoxifen and raloxifene. These medications block estrogen in breast cancer cells. A person should weigh the benefits of taking them against the side effects and risks.

Another preventive class of medications is aromatase inhibitors. These lower estrogen levels in postmenopausal females. While some research suggests they can reduce the risk, they also have side effects. They may be an option for people who cannot tolerate tamoxifen or raloxifene.

Lifestyle changes

The American Cancer Society recommends:

  • getting regular exercise
  • maintaining a healthy weight
  • limiting alcohol consumption.

Prophylactic surgery

Prophylactic refers to a measure that prevents rather than treats disease. A prophylactic bilateral mastectomy is the removal of both breasts to decrease breast cancer risk. Doctors are more likely to recommend this if a person has additional risk factors for breast cancer, such as a certain gene mutation.

A 2017 population study reviewed data concerning the treatment of LCIS in cases between 2004 and 2013. The research cites an older 2005 study that found the risk of developing breast cancer after an LCIS diagnosis was 7.1% at 10 years.

The authors of the study also mention a 2017 analysis that found that females with LCIS who develop breast cancer usually get an early-stage diagnosis. The outlook for LCIS is encouraging, considering the 10- and 20-year breast cancer-specific survival rate was 98.9% and 96.3%, respectively.

Although LCIS is not invasive breast cancer, it increases a person’s risk of developing the disease. It has no symptoms, so doctors usually diagnose it when they perform a biopsy for another breast-related condition.

Treatment may consist of surgically removing the abnormal cells along with a small amount of healthy tissue surrounding them. To reduce the risk of breast cancer, doctors may also recommend a person take estrogen-blocking or estrogen-reducing medications because the hormone may impact breast cancer cell growth.

Aside from surgical removal and medications, doctors may recommend lifestyle changes, such as exercising regularly. If someone has other risk factors for breast cancer, doctors may suggest prophylactic surgical removal of both breasts.