Breast cancer in situ

Breast cancer in situ comprises ductal carcinoma in situ (DCIS), a noninvasive breast cancer confined to the duct in which it originates, and lobular carcinoma in situ (LCIS), a neoplastic proliferation of cells in the lobules and/or terminal ducts. There are three subtypes of LCIS: classic, pleomorphic, and florid.

DCIS is frequently diagnosed during routine screening mammography. LCIS is typically asymptomatic and usually discovered incidentally.

US guidelines typically recommend offering regular (annual or biennial) bilateral mammography screening to average-risk women starting at age 40 years.

Diagnosis is with mammography, supplemented with other imaging such as ultrasound or magnetic resonance imaging, and biopsy.

Treatment of low-risk DCIS is usually lumpectomy (breast-conserving surgery) followed by radiation therapy. Pleomorphic and florid LCIS should be managed like DCIS. Classic LCIS is often managed conservatively.

Chemoprophylaxis (e.g., with tamoxifen, raloxifene, or an aromatase inhibitor [anastrozole or exemestane]) can be used in high-risk patients. Some high-risk patients may choose to undergo preventive bilateral total mastectomy.

Breast cancer comprises DCIS and LCIS (classic, pleomorphic, florid).

DCIS is a noninvasive breast cancer that is confined to the duct in which it originated and does not extend beyond the basement membrane.[1]Olivotto I, Levine M; Steering Committee on Clinical Practice Guidelines for the Care and Treatment of Breast Cancer. Clinical practice guidelines for the care and treatment of breast cancer: the management of ductal carcinoma in situ (summary of the 2001 update). CMAJ. 2001 Oct 2;165(7):912-3. https://www.cmaj.ca/content/165/7/912.long http://www.ncbi.nlm.nih.gov/pubmed/11599333?tool=bestpractice.com ​ The cancer does not have access to distant spread through lymphatics or the bloodstream. DCIS is a potential precursor of invasive carcinoma; risk of invasive breast cancer in women with DCIS is higher than in the general population.[2]Mannu GS, Wang Z, Broggio J, et al. Invasive breast cancer and breast cancer mortality after ductal carcinoma in situ in women attending for breast screening in England, 1988-2014: population based observational cohort study. BMJ. 2020 May 27;369:m1570. https://www.bmj.com/content/369/bmj.m1570.long http://www.ncbi.nlm.nih.gov/pubmed/32461218?tool=bestpractice.com [3]Mannu GS, Wang Z, Dodwell D, et al. Invasive breast cancer and breast cancer death after non-screen detected ductal carcinoma in situ from 1990 to 2018 in England: population based cohort study. BMJ. 2024 Jan 24;384:e075498. https://www.bmj.com/content/384/bmj-2023-075498.long http://www.ncbi.nlm.nih.gov/pubmed/38267073?tool=bestpractice.com ​​[4]Hieken TJ, Cheregi J, Farolan M, et al. Predicting relapse in ductal carcinoma in situ patients: an analysis of biologic markers with long-term follow-up. Am J Surg. 2007 Oct;194(4):504-6. http://www.ncbi.nlm.nih.gov/pubmed/17826066?tool=bestpractice.com [Figure caption and citation for the preceding image starts]: Ductal carcinoma in situFrom the private collection of Dr Sauter; used with permission [Citation ends].

LCIS develops in breast lobule(s) and/or terminal ducts and is usually found incidentally. LCIS is not cancer but a pathologic description of a neoplastic proliferation of cells within lobules and/or terminal ducts, which is a risk factor for invasive breast cancer.[5]Ginter PS, D'Alfonso TM. Current concepts in diagnosis, molecular features, and management of lobular carcinoma in situ of the breast with a discussion of morphologic variants. Arch Pathol Lab Med. 2017 Dec;141(12):1668-78. https://meridian.allenpress.com/aplm/article/141/12/1668/65743/Current-Concepts-in-Diagnosis-Molecular-Features http://www.ncbi.nlm.nih.gov/pubmed/28574280?tool=bestpractice.com ​ A finding of LCIS does not imply that cancer will form at the site where it is found. Treatment for LCIS is less formalized than for DCIS.​​[Figure caption and citation for the preceding image starts]: Lobular carcinoma in situFrom the private collection of Dr Sauter; used with permission [Citation ends].