Lobular carcinoma in situ (LCIS) is when there are abnormal cells in the lobules of the breast. The lobules are the part of the breast that produces milk. LCIS is not cancer. However, it can raise the risk of future breast cancer.


It is not clear what causes LCIS. It is likely due to a change in a gene.

Risk Factors

LCIS is more common in premenopausal women between 40 to 50 years old.


LCIS does not have symptoms.


LCIS does not appear on imaging tests. It cannot be felt during a breast exam. It is usually found during a biopsy of other nearby breast tissue.


LCIS does not require treatment.

The doctor will monitor the breast for changes with:

  • A physical and breast exam every 6 to 12 months
  • A yearly mammogram


The risk of breast cancer may be reduced by:

  • Reaching and keeping a healthy weight
  • Regular physical activity
  • Eating a healthful diet
  • Avoiding alcohol or—or limiting it to 1 drink or less per day

American Cancer Society

National Cancer Institute


Canadian Cancer Society

Health Canada


LCIS—lobular carcinoma in situ. Breast Cancer website. Available at: Accessed March 19, 2021.

Lobular carcinoma in situ. EBSCO DynaMed website. Available at: Accessed March 19, 2021.

Lobular carcinoma in situ (LCIS). American Cancer Society website. Available at: Accessed March 19, 2021.

Wen HY, Brogi E. Lobular carcinoma in situ. Surg Pathol Clin. 2018;11(1):123-145.

Last reviewed January 2021 by EBSCO Medical Review Board Mohei Abouzied, MD, FACP  Last Updated: 3/19/2021