Ductal carcinoma in situ (DCIS)
DCIS is abnormal cells confined to the milk ducts; it is not yet invasive cancer and cannot spread, but some of it would become invasive if left. Treatment, usually lumpectomy with radiotherapy or mastectomy, is very effective, so the live question is which low-risk DCIS can safely be watched. The first randomised trial of active monitoring (2024) found it was not worse at two years.
Overview
Ductal carcinoma in situ is a non-obligate precursor of invasive breast cancer: neoplastic epithelial cells fill the ducts without breaching the basement membrane. It is almost always detected as microcalcifications on screening mammography, is graded low, intermediate or high by nuclear grade and necrosis, and is characterised by ER, PR and HER2 status. Natural-history data from misdiagnosed or untreated cases and from autopsy series show that a substantial share of low-grade DCIS never progresses, which makes overdiagnosis and overtreatment the central problem of the disease.
Standard treatment is breast-conserving surgery with clear margins (2 mm) followed by whole-breast radiotherapy, which halves local recurrence (about half of recurrences being invasive) without affecting survival, or mastectomy for extensive disease; sentinel node biopsy is done only with mastectomy or suspicion of invasion. Adjuvant endocrine therapy (tamoxifen, or an aromatase inhibitor in postmenopausal women per NSABP B-35 and IBIS-II DCIS) reduces ipsilateral and contralateral events in ER-positive DCIS. Genomic assays (Oncotype DX DCIS Score, DCISionRT) and clinicopathological tools help identify women who can omit radiotherapy. Three randomised trials test active monitoring against surgery for low-risk DCIS: COMET (US; JAMA, December 2024) reported that active monitoring was non-inferior for the two-year rate of ipsilateral invasive cancer, LORIS (UK) and LORD (Netherlands, now including a patient-preference cohort) continue to follow patients. Longer follow-up is needed before monitoring becomes routine, but the results have already changed how DCIS is discussed with patients.
The frontier is a risk-stratified approach in which high-grade or HER2-positive DCIS is treated fully while low-risk lesions are watched, informed by molecular classifiers and, potentially, by preventive vaccines against HER2 or other DCIS antigens.
State of the art today
- COMET is the first randomised evidence that low-risk DCIS can be monitored rather than operated on, at least in the short term; LORIS and LORD will add longer follow-up.
- Genomic assays and validated clinicopathological criteria let many women omit radiotherapy after lumpectomy.
- Hypofractionated and partial-breast radiotherapy shorten treatment for those who need it; low-dose tamoxifen cuts side effects.
- DCIS is the clearest example of the overdiagnosis problem in oncology and the test bed for risk-stratified de-escalation.
Where it starts and where it drains
Most cancers start in the ducts and drain first to the axillary nodes, which is why the armpit is checked and a sentinel node is sampled.
- Ducts (most cancers start here)Low-grade DCIS (often ER-positive) · Intermediate-grade DCIS · High-grade DCIS with comedo necrosis (often HER2-positive) · DCIS with microinvasion (staged as T1mi) · Paget disease of the nipple (DCIS extending to nipple skin)
- Lobules (lobular carcinoma)
- Upper outer quadrant (commonest site)
- Nipple-areolaPaget disease of the nipple (DCIS extending to nipple skin)
- axillary level I
- axillary level II-III
- internal mammary
- supraclavicular
Same organ: Triple-negative breast cancer (TNBC), HR-positive / HER2-negative breast cancer, HER2-positive breast cancer, Male breast cancer
About one in five to one in four breast cancers detected by mammographic screening is DCIS; it was rare before screening and is now diagnosed in tens of thousands of women a year in the US alone (SEER; NCI).
- AI in radiologyEstablished
- Mammography & tomosynthesisStandard of care
- cfDNA fragmentomicsEstablished
- Colorectal cancer screening (colonoscopy, FIT, stool DNA, blood)Standard of care
- DNA methylation profilingEstablished
- HCC surveillance in cirrhosis (ultrasound + AFP)Standard of care
- A 28-day national pathway for people with a positive multi-cancer blood test
- A breath test to rule out cancer in people with vague symptoms
- A cancer blood test for older people arriving at A&E with unexplained symptoms
- A legislated, publicly reported 28-day standard from urgent referral to diagnosis
- A live national dashboard of stage at diagnosis as the scorecard for early detection
- A single 'cancer check at 60' appointment bundling all screening tests
Background: Alpha-fetoprotein (AFP), Barrett's oesophagus, CA 19-9, Early detection, Faecal immunochemical test (FIT). Also on OnCo: Symptoms and red flags · Early detection roadmap.
Where the cases are
No country-level case numbers. This cancer is not mapped to a GLOBOCAN site.
Lumpectomy to 2 mm margins followed by whole-breast radiotherapy (hypofractionated), with radiotherapy omission considered for low-risk lesions (RTOG 9804 criteria or genomic assay).
Mastectomy with sentinel node biopsy and optional reconstruction; radiotherapy not needed after mastectomy with clear margins.
Tamoxifen (or anastrozole in postmenopausal women) for five years to reduce ipsilateral and contralateral breast events; low-dose tamoxifen is an option (TAM-01).
Active monitoring with mammography every six months and optional endocrine therapy, in trials (COMET, LORIS, LORD) or after shared decision-making where guidelines allow.
Subtypes & biomarkers
top- Low-grade DCIS (often ER-positive)
- Intermediate-grade DCIS
- High-grade DCIS with comedo necrosis (often HER2-positive)
- DCIS with microinvasion (staged as T1mi)
- Paget disease of the nipple (DCIS extending to nipple skin)
- Nuclear grade and necrosis
- ER and PR status
- HER2 status (not used to select therapy outside trials)
- Margin width (2 mm standard after breast conservation)
- Oncotype DX DCIS Score or DCISionRT (radiotherapy omission decisions)
- Extent on mammography and MRI
Target prevalence in this cancer
- 1932Broders defines carcinoma in situ
The concept of non-invasive cancer confined by the basement membrane.
- 1985Screening mammography makes DCIS common
Incidence rises several-fold in screened populations.
- 1993NSABP B-17: radiotherapy after lumpectomy for DCIS
Halves local recurrence; no survival difference.
- 1999NSABP B-24: tamoxifen after lumpectomy plus radiotherapy
- 2015Anastrozole versus tamoxifen for DCIS (NSABP B-35, IBIS-II DCIS)
Aromatase inhibitor an alternative in postmenopausal women.
- 20162 mm margin standard (SSO-ASTRO-ASCO)
- 2024COMET: active monitoring non-inferior at two years
Hwang and colleagues (JAMA, December 2024); first randomised evidence for monitoring low-risk DCIS.
Open problems, and what is being done about each
Distinguishing DCIS that would progress from DCIS that would not; molecular classifiers, mammographic AI and the monitoring trials are the route.
Long-term safety of active monitoring beyond two years; LORIS and LORD follow-up and the COMET ten-year endpoint will tell.
Overtreatment by mastectomy remains common; shared decision aids and radiotherapy omission tools are the response.
Preventing progression pharmacologically or with vaccines (HER2-directed DCIS vaccine trials) rather than surgically.
Trials
topRecruiting now (live from ClinicalTrials.gov)
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Expert centres
topCentres linked to this cancer in OnCo
- via Sentinel lymph node biopsy
- NSABP FoundationPittsburgh, PA, USvia Oncotype DX, Sentinel lymph node biopsy, Endocrine therapy (SERMs, AIs, SERDs)
- via IMRT / IGRT (modern external beam), Mammography & tomosynthesis
- Aarhus University HospitalAarhus, DKvia IMRT / IGRT (modern external beam)
- Alliance for Clinical Trials in OncologyChicago, IL, USvia Sentinel lymph node biopsy
- American Society for Radiation OncologyArlington, VA, USvia IMRT / IGRT (modern external beam)
- via Endocrine therapy (SERMs, AIs, SERDs)
- via Endocrine therapy (SERMs, AIs, SERDs)
- via Endocrine therapy (SERMs, AIs, SERDs)
- Breast Cancer TrialsNewcastle, NSW, AUvia Endocrine therapy (SERMs, AIs, SERDs)
- Centre Antoine LacassagneNice, FRvia IMRT / IGRT (modern external beam)
- Centre Oscar LambretLille, FRvia IMRT / IGRT (modern external beam)
- via IMRT / IGRT (modern external beam)
- via IMRT / IGRT (modern external beam)
- Comprehensive Cancer Center Freiburg (CCCF)Freiburg im Breisgau, DEvia IMRT / IGRT (modern external beam)
- via Endocrine therapy (SERMs, AIs, SERDs)
- Dan L Duncan Comprehensive Cancer Center, Baylor College of MedicineHouston, TX, USNCI comprehensivevia Endocrine therapy (SERMs, AIs, SERDs)
- via Overdiagnosis and false alarms
- ECOG-ACRIN Cancer Research GroupPhiladelphia, PA, USvia Mammography & tomosynthesis
- Edinburgh Cancer Centre / CRUK Scotland CentreEdinburgh, GBvia Endocrine therapy (SERMs, AIs, SERDs)
- ETOP IBCSG Partners FoundationBern, CHvia Endocrine therapy (SERMs, AIs, SERDs)
- European Society for Radiotherapy and OncologyBrussels, BEvia IMRT / IGRT (modern external beam)
- European Society of Surgical OncologyBrussels, BEvia Sentinel lymph node biopsy
- GEICAM Spanish Breast Cancer GroupMadrid, ESvia Endocrine therapy (SERMs, AIs, SERDs)
- Geneva University Hospitals (HUG)Geneva, CHvia IMRT / IGRT (modern external beam)
- via Endocrine therapy (SERMs, AIs, SERDs)
- Groote Schuur Hospital / University of Cape TownCape Town, ZAvia IMRT / IGRT (modern external beam)
- via IMRT / IGRT (modern external beam)
- Hacettepe University Cancer InstituteAnkara, TRvia IMRT / IGRT (modern external beam)
- via IMRT / IGRT (modern external beam)
- Ho Chi Minh City Oncology HospitalHo Chi Minh City, VNvia IMRT / IGRT (modern external beam)
- Hokkaido University HospitalSapporo, JPvia IMRT / IGRT (modern external beam)
- Hospital de Amor (Barretos Cancer Hospital)Barretos, BRvia Mammography & tomosynthesis
- Hunan Cancer HospitalChangsha, CNvia IMRT / IGRT (modern external beam)
- Institut BergoniéBordeaux, FRvia IMRT / IGRT (modern external beam)
- Institut Jules BordetBrussels, BEvia Endocrine therapy (SERMs, AIs, SERDs)
- Institut National d'Oncologie, RabatRabat, MAvia IMRT / IGRT (modern external beam)
- Institut Salah AzaïezTunis, TNvia IMRT / IGRT (modern external beam)
- Institute of Oncology LjubljanaLjubljana, SIvia IMRT / IGRT (modern external beam)
- via IMRT / IGRT (modern external beam)
- via IMRT / IGRT (modern external beam)
- International Extranodal Lymphoma Study GroupBellinzona, CHvia IMRT / IGRT (modern external beam)
- IRCCS Humanitas Research HospitalRozzano (Milan), ITvia IMRT / IGRT (modern external beam)
- Istanbul University Institute of OncologyIstanbul, TRvia IMRT / IGRT (modern external beam)
- via IMRT / IGRT (modern external beam)
- Juravinski Cancer Centre / Escarpment Cancer Research InstituteHamilton, ON, CAvia IMRT / IGRT (modern external beam)
- Kaiser Permanente Division of ResearchOakland, CA, USvia Mammography & tomosynthesis
- Keio University HospitalTokyo, JPvia Sentinel lymph node biopsy
- Kenyatta National HospitalNairobi, KEvia IMRT / IGRT (modern external beam)
- Korle Bu Teaching HospitalAccra, GHvia IMRT / IGRT (modern external beam)
- Lagos University Teaching HospitalLagos, NGvia IMRT / IGRT (modern external beam)
- via IMRT / IGRT (modern external beam)
- via IMRT / IGRT (modern external beam)
- via IMRT / IGRT (modern external beam)
- via Oncotype DX
- MovemberMelbourne, AUvia Overdiagnosis and false alarms
- National Cancer Center KoreaGoyang, KRvia Mammography & tomosynthesis
- via IMRT / IGRT (modern external beam)
- National Institute of Oncology, HungaryBudapest, HUvia IMRT / IGRT (modern external beam)
- via IMRT / IGRT (modern external beam)
- Ocean Road Cancer InstituteDar es Salaam, TZvia IMRT / IGRT (modern external beam)
- via IMRT / IGRT (modern external beam)
- Rajiv Gandhi Cancer Institute and Research CentreNew Delhi, INvia IMRT / IGRT (modern external beam)
- Rambam Health Care CampusHaifa, ILvia IMRT / IGRT (modern external beam)
- Rigshospitalet – Copenhagen University HospitalCopenhagen, DKvia IMRT / IGRT (modern external beam)
- Royal Adelaide HospitalAdelaide, AUvia IMRT / IGRT (modern external beam)
- via IMRT / IGRT (modern external beam)
- Siriraj Hospital, Mahidol UniversityBangkok, THvia IMRT / IGRT (modern external beam)
- Society of Surgical OncologyRosemont, IL, USvia Sentinel lymph node biopsy
- Tata Medical Center, KolkataKolkata, INvia IMRT / IGRT (modern external beam)
- Tawam HospitalAl Ain, AEvia IMRT / IGRT (modern external beam)
- Tel Aviv Sourasky Medical CenterTel Aviv, ILvia IMRT / IGRT (modern external beam)
- TROG Cancer ResearchNewcastle, NSW, AUvia IMRT / IGRT (modern external beam)
- UMC Utrecht Cancer CenterUtrecht, NLvia IMRT / IGRT (modern external beam)
- University of Malaya Medical CentreKuala Lumpur, MYvia IMRT / IGRT (modern external beam)
- via IMRT / IGRT (modern external beam)
- via Tamoxifen
- Velindre Cancer CentreCardiff, GBvia IMRT / IGRT (modern external beam)
- via IMRT / IGRT (modern external beam)
- via Oncotype DX
- Zhejiang Cancer HospitalHangzhou, CNvia IMRT / IGRT (modern external beam)
Questions to ask
topQuestions to ask your oncologist about Ductal carcinoma in situ
Newly diagnosed
- What is my exact diagnosis, stage, and grade, and which tests established them?Why: Everything else follows from an accurate stage and subtype.
- Which biomarkers have been tested on my tumour (for example Nuclear grade and necrosis, ER and PR status, HER2 status, Margin width, Oncotype DX DCIS Score or DCISionRT), and what were the results?Why: These results decide eligibility for targeted therapy, immunotherapy, and trials.
- Which subtype is my cancer, and does that change the recommended treatment?Why: Recognised subtypes for this cancer include Low-grade DCIS, Intermediate-grade DCIS, High-grade DCIS with comedo necrosis.
- Is germline (inherited) genetic testing recommended for me or my family?Why: Inherited variants can change treatment and matter for relatives.
Localised DCIS, breast conservation
- For my situation (localised dcis, breast conservation), which of the standard options do you recommend and why?Why: Guideline options include: Lumpectomy to 2 mm margins followed by whole-breast radiotherapy (hypofractionated), with radiotherapy omission considered for low-risk lesions (RTOG 9804 criteria or genomic assay).
- Am I a candidate for Oncotype DX, and what side effects should I expect?Why: Knowing the expected toxicities helps you plan work, family, and supportive care.
Extensive or multicentric DCIS
- For my situation (extensive or multicentric dcis), which of the standard options do you recommend and why?Why: Guideline options include: Mastectomy with sentinel node biopsy and optional reconstruction; radiotherapy not needed after mastectomy with clear margins.
ER-positive DCIS after breast conservation
- For my situation (er-positive dcis after breast conservation), which of the standard options do you recommend and why?Why: Guideline options include: Tamoxifen (or anastrozole in postmenopausal women) for five years to reduce ipsilateral and contralateral breast events; low-dose tamoxifen is an option (TAM-01).
- Am I a candidate for Tamoxifen, and what side effects should I expect?Why: Knowing the expected toxicities helps you plan work, family, and supportive care.
Low-risk DCIS
- For my situation (low-risk dcis), which of the standard options do you recommend and why?Why: Guideline options include: Active monitoring with mammography every six months and optional endocrine therapy, in trials (COMET, LORIS, LORD) or after shared decision-making where guidelines allow.
Any stage
- Are there clinical trials I could join, for example of Active surveillance, Oncotype DX, Tamoxifen?Why: Trials are how the next standard of care is set; asking early keeps options open.
- Would a second opinion at a high-volume centre change anything, and can you help arrange it?Why: Rare or high-stakes decisions benefit from a centre that treats many similar patients.
- What supportive care (symptom control, nutrition, exercise, mental health, financial help) is available from the start?Why: Supportive care improves quality of life and helps patients complete treatment.
- I read that “Distinguishing DCIS that would progress from DCIS that would not; molecular classifiers, mammographic AI and the monitoring trials are the route”. How does that affect my plan?Why: Open problems are where trials and second opinions matter most.
- I read that “Long-term safety of active monitoring beyond two years; LORIS and LORD follow-up and the COMET ten-year endpoint will tell”. How does that affect my plan?Why: Open problems are where trials and second opinions matter most.
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Direct links plus the targets, companies, and technologies of this cancer's products.
technologies
10targets
2drugs
3companies
2pathways
1terms
5bottlenecks
2Latest papers
topQuery for this cancer: (TITLE:"Ductal carcinoma in situ" OR ABSTRACT:"Ductal carcinoma in situ" OR TITLE:"DCIS" OR ABSTRACT:"DCIS" OR TITLE:"Stage 0 breast cancer" OR ABSTRACT:"Stage 0 breast cancer" OR TITLE:"Pre-invasive breast cancer" OR ABSTRACT:"Pre-invasive breast cancer" OR TITLE:"Intraductal carcinoma" OR ABSTRACT:"Intraductal carcinoma") AND (treatment OR therapy OR trial OR survival OR diagnosis). Results are unfiltered search hits about Ductal carcinoma in situ (DCIS), not a curated reading list.
Pages like this
not linked directly; found by shared links- PersonConstance D. Lehman
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- PersonAditya Bardia
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- PersonKristina Lång
Shares Mammography & tomosynthesis, AI in radiology, HR-positive / HER2-negative breast cancer and the tag breast.