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 cancer.

Most cases of LCIS occur before menopause [267]. The average age at diagnosis is 44-46 years [267].

The following is a 3D interactive model showing LCIS. The labels show a normal lobe and a lobe with LCIS.

Learn more about breast anatomy.

LCIS and breast cancer risk  

Women with LCIS have an increased risk of invasive breast cancer [267-269].

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) [267-268].

Women diagnosed with LCIS have [267,270-271]:

  • About a 10% chance of developing ductal carcinoma in situ (DCIS) or invasive breast cancer in 10 years
  • About a 20% chance of developing DCIS or invasive breast cancer in 20 years

Women with LCIS can develop invasive lobular cancer or invasive ductal cancer [267-268].

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) [267,271-273].

Learn about invasive lobular cancer and other types of tumors.

Learn about other factors linked to the risk of breast cancer.

LCIS and breast cancer screening

There are special breast cancer screening guidelines for women with LCIS who also have a 20% or greater lifetime risk of breast cancer. (Estimate your lifetime risk or learn more about risk.)

The National Comprehensive Cancer Network (NCCN) recommends women with LCIS who also have a 20% or greater lifetime risk of breast cancer [163]:

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

The NCCN recommends women with LCIS who have a less than 20% lifetime risk of invasive breast cancer get the same breast cancer screening as women at average risk.

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

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

Both tamoxifen and raloxifene can lower the risk of [232]:

Learn more about risk-lowering drugs.


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

Preventive surgery (risk-reducing 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 people at higher risk.  

Find questions about LCIS for your health care provider.

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

Learn more about talking with your health care provider.  

Susan G. Komen® Support Resources

 Updated 03/30/23