Summary
Definition
Breast cancer in situ is cancer that is confined to the duct or lobule in which it originated and does not extend beyond the basement membrane. The cancer does not have access to distant spread through lymphatics or the bloodstream. Ductal carcinoma in situ (DCIS) is a potential precursor of invasive carcinoma and suggests that cancer will become invasive at that site.[1]
[Figure caption and citation for the preceding image starts]: Ductal carcinoma in situFrom the private collection of Dr Sauter; used with permission [Citation ends].
Lobular carcinoma in situ (LCIS) develops in breast lobule(s) and is usually found incidentally. 
[Figure caption and citation for the preceding image starts]: Lobular carcinoma in situFrom the private collection of Dr Sauter; used with permission [Citation ends]. Whereas DCIS predicts an increased risk of invasive ductal carcinoma developing at the site of a biopsy demonstrating DCIS, LCIS implies increased risk of invasive ductal or lobular carcinoma developing in either breast.[2] LCIS does not behave physiologically like cancer: cancer may never form, but LCIS is nevertheless a marker for increased risk. Similarly, a finding of LCIS does not imply that cancer will form at the diagnostic site. Consequently, treatment for LCIS is less formalized than for DCIS.
History and exam
Risk factors
- family history of breast cancer
- benign breast disease on prior biopsy
- older age at menopause
- older age at first full-term pregnancy
- nulliparity
- low physical activity
- high vitamin A intake
- hereditary breast ovarian cancer syndrome
- Li-Fraumeni syndrome
- Cowden syndrome
- Klinefelter syndrome
- ataxia telangiectasia
- Peutz-Jeghers syndrome
Diagnostic investigations
Investigations to consider
- biopsy (fine-needle or core)
- stereotactic biopsy
- sentinel node biopsy
- ultrasound-guided biopsy
- magnetic resonance imaging (MRI)
- ultrasonography
- hormone receptor testing
- genetic testing for BRCA
Treatment algorithm
Contributors
AuthorsVIEW ALL
Director of Breast Surgery
Hartford Healthcare
Hartford
CT
Disclosures
ERS is an author of a reference cited in this monograph.
Dr Edward R. Sauter would like to gratefully acknowledge Dr Rachel L. Ruhlen, a previous contributor to this monograph. RLR declares that she has no competing interests.
Peer reviewersVIEW ALL
Radiologist
Radboud University Nijmegen Medical Centre
Nijmegen
The Netherlands
Disclosures
CB is an author of a number of references cited in this monograph.
Assistant in the Division of Medical Oncology
European Institute of Oncology
Milan
Italy
Disclosures
AB declares that she has no competing interests.
Associate Professor in Epidemiology and Medical Oncology
Johns Hopkins School of Medicine and Bloomberg School of Public Health
Baltimore
MD
Disclosures
KV declares that she has no competing interests.
Consultant Surgeon and Honorary Senior Lecturer
Edinburgh Breast Unit
Western General Hospital
Edinburgh
UK
Disclosures
GTN is a principal investigator for the IBIS-II trial, and is an author of a guideline cited in this monograph.
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