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 invasive breast cancer.

Most cases of LCIS occur before menopause [209]. The average age at diagnosis is 44-46 years [209].

Image source: National Cancer Institute (www.cancer.gov)

Learn more about breast anatomy.

LCIS and breast cancer risk  

LCIS increases the risk of invasive breast cancer.

Compared to women without LCIS, those with LCIS are 7-11 times more likely to develop invasive cancer in either breast [209-210].

Women diagnosed with LCIS have an estimated [211]:

• 11 percent chance of developing breast cancer in 10 years
• 20 percent chance of developing breast cancer in 20 years

Women with LCIS can develop invasive lobular cancer or invasive ductal cancer [210].

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) [210,212-214]. 

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.

It's recommended that women with LCIS [145]:

• Have a clinical breast exam every 6-12 months
• Have a mammogram every year, starting at age 30 (3D mammography (breast tomosynthesis) may be considered) 
• Talk with their health care providers about screening with breast MRI every year, starting at age 25;

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

Risk-lowering drugs

Tamoxifen and raloxifene

It’s strongly recommended that women with LCIS take tamoxifen or raloxifene to lower their risk of breast cancer [175]. 

Both tamoxifen and raloxifene can lower the risk of [215]:

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

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

Both pre- and postmenopausal women can take tamoxifen. Raloxifene is only for use among postmenopausal women.

Tamoxifen and raloxifene only reduce the risk of estrogen receptor-positive breast cancers. Neither drug reduces the risk of estrogen receptor-negative cancers [215].

Although raloxifene is slightly less effective than tamoxifen in reducing the risk of breast cancer, it has fewer harmful health effects [215]. 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 [215].

Learn more about tamoxifen and raloxifene.  

Aromatase inhibitors

Aromatase inhibitors are hormone therapy drugs that are part of standard treatment for estrogen receptor-positive breast cancer.

Findings from randomized controlled trials have shown the aromatase inhibitors exemestane and anastrozole may lower the risk of developing breast cancer in postmenopausal women at higher risk, including women with LCIS [216-217].

Although aromatase inhibitors are FDA-approved for use in breast cancer treatment, they don't have FDA-approval for use in the risk reduction setting.

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)

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.

Today, the use of tamoxifen or raloxifene (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 [175].

Talk with your health care provider about the risks and benefits of your risk-lowering options.   

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.