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.
Image source: National Cancer Institute (www.cancer.gov)
Learn more about breast anatomy.
LCIS and breast cancer risk
Women with LCIS have an increased risk of invasive breast cancer [259-260].
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) [259-260].
Women diagnosed with LCIS have [261-262]:
- 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 .
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) [260,263-265].
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.
- 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 a health care provider about screening with breast MRI every year, starting at age 25
This medical care helps ensure if breast cancer does develop, it’s caught at an early stage 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
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.
Tamoxifen and raloxifene
It’s strongly recommended women with LCIS take tamoxifen or raloxifene to lower their risk of breast cancer .
Both tamoxifen and raloxifene can lower the risk of :
- 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.
Tamoxifen and raloxifene only reduce the risk of estrogen receptor-positive breast cancers. Neither drug reduces the risk of estrogen receptor-negative cancers .
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 . 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 .
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 are hormone therapy drugs used to treat 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 [266-267].
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 at higher risk of breast cancer.
However, these drugs do not have FDA-approval for use in the risk reduction setting. They are only FDA-approved for use in breast cancer treatment.
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.
Learn more about options for women at higher risk.
Learn more about talking with your health care provider.
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