The Who, What, Where, When and Sometimes, Why.

Lobular Carcinoma in Situ (LCIS)

What is lobular carcinoma in situ (LCIS)?

The lobules of the breast are small, round sacs that produce milk for breastfeeding.

When abnormal cells grow inside the lobules, but have not spread to nearby tissue or beyond, the condition is called lobular carcinoma in situ (LCIS). The term “in situ” means “in place.” With LCIS, the abnormal cells are still “in place” inside the lobules.

Although the term LCIS includes the word “carcinoma,” LCIS is not breast cancer.

Most cases of LCIS occur before menopause [271]. The average age at diagnosis is 44-46 years [271]. LCIS is more common in white women than in African American women in the U.S. [271].


Image source: National Cancer Institute (

Learn more about breast anatomy.

LCIS and breast cancer risk  

Women with LCIS have an increased risk of invasive breast cancer [271-273].

Compared to women without LCIS, those with LCIS are 7-11 times more likely to develop invasive cancer in either breast (the breast with LCIS or the opposite breast) [271-272].

Women diagnosed with LCIS have [271,274]:

  • About a 10 percent chance of developing breast cancer in 10 years
  • About a 20 percent chance of developing breast cancer in 20 years

Women with LCIS can develop invasive lobular cancer or invasive ductal cancer [271-272].

In the past, LCIS was not considered to be a precursor (a condition that can develop into) to breast cancer. However, some studies show LCIS may develop into invasive lobular cancer (invasive breast cancer that begins in the lobules) [271,275-277].

Learn about invasive lobular cancer and other types of tumors.

LCIS and breast cancer screening

There are special breast cancer screening guidelines for women with LCIS.

The National Comprehensive Cancer Network (NCCN) recommends women with LCIS [162]:

This medical care helps ensure if breast cancer does develop, it’s caught early when the chances of survival are highest.

Learn more about breast cancer screening recommendations for women at higher risk.

Risk-lowering options for women with LCIS who do not have breast cancer

Talk with your health care provider about the risks and benefits of your risk-lowering options to choose the one that’s right for you.

Risk-lowering drugs for women with LCIS

Tamoxifen and raloxifene

It’s strongly recommended women with LCIS take a risk-lowering drug (such as tamoxifen) to lower their risk of breast cancer [193].

Tamoxifen and raloxifene are the only drugs FDA-approved for lowering the risk of breast cancer (for women who do not have breast cancer), but are at higher risk of breast cancer.

Both tamoxifen and raloxifene can lower the risk of [234]:

Tamoxifen and raloxifene are the only drugs FDA-approved for breast cancer risk reduction.

Tamoxifen and raloxifene only reduce the risk of estrogen receptor-positive breast cancers. Neither drug reduces the risk of estrogen receptor-negative cancers [234].

Both premenopausal women and postmenopausal women can take tamoxifen. Only postmenopausal women can take raloxifene.

Tamoxifen is more effective than raloxifene in lowering breast cancer risk, but raloxifene has fewer harmful side effects [234]. This makes raloxifene a better choice for some women.

For example, tamoxifen increases the risk of cataracts and cancer of the uterus, but raloxifene does not. Tamoxifen also increases the risk of blood clots in the lungs and large veins more than raloxifene [234].

Both drugs can cause menopausal symptoms such as hot flashes.

Learn more about tamoxifen and raloxifene.  

Learn more about the side effects of tamoxifen and raloxifene.

Learn about treating menopausal symptoms.


For a summary of studies on tamoxifen and raloxifene, visit the Breast Cancer Research Studies section.

Aromatase inhibitors

Aromatase inhibitors are hormone therapy drugs used to treat estrogen receptor-positive breast cancer.

Exemestane and anastrozole are aromatase inhibitor drugs. Findings from randomized controlled trials have shown exemestane and anastrozole may lower the risk of developing breast cancer in postmenopausal women at higher risk, including women with LCIS [235-236].

The American Society for Clinical Oncology (ASCO), the National Comprehensive Cancer Network (NCCN) and the U.S. Preventive Services Task Force list exemestane and anastrozole as risk-lowering drug options for postmenopausal women who do not have breast cancer, but are at higher risk of breast cancer.

However, these drugs do not have FDA-approval for use in the risk reduction setting. They’re only FDA-approved for use in breast cancer treatment.

Learn about emerging areas in risk reduction for women at higher risk of breast cancer.

Learn about aromatase inhibitors and breast cancer treatment.

Preventive surgery (prophylactic mastectomy)

Today, the use of a risk-lowering drug (along with recommended breast cancer screening to find breast cancer early if it develops) is the preferred option for lowering risk in women with LCIS [193].

In the past, prophylactic bilateral mastectomy (surgery to remove both breasts) was considered for women with LCIS to lower breast cancer risk as much as possible. This is now discouraged since the risk reduction benefits from a risk-lowering drug and surgery are similar [193].

Learn more about options for women at higher risk.  

Find questions about LCIS for your health care provider.

Learn more about talking with your health care provider.  


  • If you or a loved one needs more information about breast health or breast cancer, call the Komen Breast Care Helpline at 1-877 GO KOMEN (1-877-465-6636). All calls are answered by a trained specialist or oncology social worker in English and Spanish, Monday through Friday from 9:00 a.m. to 10:00 p.m. ET. You can also email the helpline at Se habla español.
  • We offer an online support community through our closed Facebook Group – Komen Breast Cancer group. The Facebook group provides a place where those with a connection to breast cancer can discuss each other’s experiences and build strong relationships to provide support to each other. Visit Facebook and search for “Komen Breast Cancer group” to request to join the closed group.
  • Our fact sheets, booklets and other education materials offer additional information. 

 Updated 03/14/22