The short answer
Lobular carcinoma in situ, or LCIS, means abnormal cells are found in the lobules of the breast. NCI says it raises the risk of breast cancer in either breast. NCI's professional staging summary calls it a benign entity. This page explains the term and what to ask your care team.
NCI defines LCIS as abnormal cells found in the lobules of the breast.
NCI says having LCIS in one breast raises the risk of breast cancer in either breast.
NCI's professional summary says LCIS is a benign entity and was removed from TNM staging.
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This page is for anyone whose breast biopsy report says "lobular carcinoma in situ" or "LCIS." It explains the term and what to ask your care team.
What LCIS means
NCI describes LCIS as a breast condition in which abnormal cells are found in the lobules. Lobules are the small glands that make milk.
Is it cancer?
The name includes "carcinoma," which can be alarming. NCI's breast cancer summary for health professionals says: "Lobular carcinoma in situ is a benign entity and is removed from TNM staging." Benign means not cancer.
Why it still matters
NCI says LCIS significantly raises the risk of breast cancer in either breast. That is why your care team may talk with you about follow-up and screening.
LCIS is not the same as invasive lobular carcinoma
Invasive lobular carcinoma is a breast cancer. LCIS is a different finding. Ask your care team to confirm which term is on your report.
Ask these before you leave
- Is LCIS the only finding on my report?
- What does it mean for my breast cancer risk?
- What follow-up or screening do you recommend for me?
Related pages
See What Does DCIS Mean?, Atypical Ductal Hyperplasia, and Invasive Lobular Carcinoma on Your Pathology Report.
Sources
Common questions
Is LCIS cancer?
Despite the name, NCI's professional breast summary calls LCIS a benign entity and notes it was removed from TNM staging. Ask your care team what it means for you.
Does LCIS turn into cancer?
NCI says having it raises the risk of breast cancer in either breast. Ask your care team what your follow-up should be.
How is LCIS different from DCIS?
LCIS is in the lobules, the milk-making glands. DCIS is in the lining of the ducts. Ask your care team which one your report shows.
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Sources last checked: 2026-10-02 what this meansLast updated: 2026-10-02Next planned review: 2027-09-27
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Cancer Explained does not originate medical claims. Every page restates guidance already published by the National Cancer Institute, the CDC, the USPSTF and the FDA, in plain language, with the source cited so you can check the original yourself. AI does the translating and organizing; automated checks test claims, citations, clarity and safety before anything publishes, and this is translation and navigation, not clinical judgment. Nothing here is personal medical advice, and no page can account for your particular situation.
Editorial status: Source checked — This page was written with AI assistance and then compared with the sources listed on it, looking for statements those sources do not back up. That check is not a sentence-by-sentence record and can miss errors. It is not a medical review, and it does not confirm the page is complete or right for your situation.
Human medical review: not completed. Pages here are not signed off by a clinician before they publish. That is not an oversight we are quietly working around: we restate published guidance and cite it, so the authority belongs to the source rather than to us, and every page names where its claims come from — you can verify us instead of trusting us. Where a volunteer clinician has reviewed a page, their name and credentials appear on it; where no name appears, no clinician has checked it. We are glad to have reviewers and are recruiting them, and we do not hold pages back waiting for one. Use this site to understand your situation and to ask better questions of the people treating you.
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