Breast Cancer Risk Factors: Lobular Carcinoma in Situ (LCIS)

What are breast lobules?

Lobules are small, round sacs in the breast that produce milk for breastfeeding. All women have lobules in their breasts, not just women who’ve been pregnant and breastfed.

Lobules are most often absent in men.

What is lobular carcinoma in situ (LCIS)?

When abnormal cells grow inside the breast 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 [254]. The average age at diagnosis is 44-46 years [254].

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 [254-256].

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) [254-255].

Women diagnosed with LCIS have [254,257-258]:

• 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 [254-255].

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) [254,258-260].

Learn about invasive lobular cancer.

Learn about invasive ductal 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]:

• Have a clinical breast exam and risk assessment every 6-12 months, starting at age 25
• Have a mammogram with digital breast tomosynthesis every year, starting at age 30 
• Talk with a health care provider about screening with breast MRI every year, starting at age 25

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

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

Risk reduction options for women with LCIS who don’t have breast cancer

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

Risk-reducing drugs for women with LCIS

The National Comprehensive Cancer Network (NCCN) strongly recommends women with LCIS take a risk-reducing drug (such as tamoxifen) to lower their risk of breast cancer [54].

Both tamoxifen and raloxifene can lower the risk of [231]:

• Invasive breast cancer
• Non-invasive breast cancers, such as ductal carcinoma in situ (DCIS)

Learn more about risk-reducing drugs.

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

Risk-reducing mastectomy (preventive surgery)

Today, the use of a risk-reducing drug (along with recommended breast cancer screening to find breast cancer early if it develops) is the preferred option over risk-reducing mastectomy for lowering risk in women with LCIS [54].

In the past, risk-reducing 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-reducing drug and surgery are similar [54].

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

Do you need more information about breast cancer risk factors? We’re here for you. The Komen Patient Care Center is your trusted, go-to source for timely, accurate breast health and breast cancer information, services and resources. Our navigators offer free, personalized support for you and your loved ones including education, emotional support, financial assistance, help accessing care and more. Get connected to a Komen navigator by contacting the Breast Care Helpline at 1-877-465-6636 or email helpline@komen.org to get started. All calls are answered Monday through Thursday, 9 a.m to 7 p.m. ET and Friday, 9 a.m. to 6 p.m. ET. Se habla español. The Komen Breast Cancer and Komen Metastatic (Stage IV) Breast Cancer Facebook groups are places where those with breast cancer and their family and friends can talk with others for friendship and support. Our fact sheets, booklets and other education materials offer additional information.

SUSAN G. KOMEN®‘S BREAST SELF-AWARENESS MESSAGES

1. Know your risk Talk with both sides of your family to learn about your family health history. Talk with a health care provider about your risk of breast cancer. 2. Get screened Talk with a health care provider about which screening tests are right for you if you’re at higher risk. Have a mammogram every year starting at age 40 if you’re at average risk.* Have a clinical breast exam at least every 3 years starting at age 25, and every year starting at age 40.* * Per National Comprehensive Cancer Network Guidelines 3. Know what is normal for you See a health care provider if you notice any of these breast changes: Lump, hard knot or thickening inside the breast or underarm area Swelling, warmth, redness or darkening of the breast Change in the size or shape of the breast Dimpling or puckering of the skin Itchy, scaly sore or rash on the nipple Pulling in of the nipple or other parts of the breast Nipple discharge that starts suddenly New pain in one spot that doesn’t go away To see illustrations of these warning signs, please visit the Warning Signs of Breast Cancer page. 4. Make healthy lifestyle choices Maintain a healthy weight. Make exercise part of your routine. Limit alcohol intake. Limit menopausal hormone therapy (postmenopausal hormone use). Breastfeed if you can.

 Updated 12/17/24

This content is regularly reviewed by an expert panel including researchers, practicing clinicians and patient advocates.