Lobules are the part of the breast that produces milk. Lobular carcinoma in situ (LCIS) is when there are abnormal cells in the lobules of the breast. These abnormal cells do not grow in an uncontrolled way or spread to other parts of the body like cancer. But, LCIS is a risk factor for 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 who are between 40-50 years old.


LCIS does not have symptoms.


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


LCIS does not require treatment.

Your doctor will monitor your breast for changes with:

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


Take these steps to reduce your overall risk of breast cancer:

  • Exercise regularly.
  • Eat a healthful diet.
  • Maintain a healthy weight.
  • Avoid or limit alcohol. This means 1 drink or less a day for women and 2 drinks or less a day for men.
  • Follow your doctor’s guidelines for regular breast cancer screening.

American Cancer Society

National Cancer Institute


Canadian Cancer Society

Health Canada


LCIS—lobular carcinoma in situ. Breast Cancer website. Available at: Update February 18, 2017. Accessed January 29, 2018.

Lobular carcinoma in situ. EBSCO DynaMed Plus website. Available at: Updated August 18, 2016. Accessed January 29, 2018.

Lobular carcinoma in situ (LCIS). American Cancer Society website. Available at: Updated September 20, 2017. Accessed January 29, 2018.

Venkitaraman, R. Lobular neoplasia of the breast. Breast J. 2010;16(5):519-528.

Last reviewed November 2018 by EBSCO Medical Review Board Mohei Abouzied, MD, FACP  Last Updated: 5/21/2018