The first 60 days: Ductal carcinoma in situ (DCIS)

What happens now

Staging tests establish exactly what and where the cancer is. Everything else follows from the answers.

Biomarkers your report may list

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

Ask which of these were tested and what the results were; see the report reader for what each value means.

Tests and imaging linked to this cancer

Active surveillance Companion diagnostics Mammography & tomosynthesis MRI AI in radiology RNA sequencing & expression profiling Gene-expression prognostic assays

Weeks 1 to 3

Who is on your team

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These specialties appear in the standard of care for this cancer. In most centres they meet weekly as a tumour board to agree each plan; you can ask when yours was discussed and what was decided.

A second opinion from a centre that treats many similar cases is normal, not rude; the standard of care tells you what to compare it against.

Weeks 2 to 6

Decisions coming up

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Each row is a setting from the standard of care, in the order it usually arises. Not all will apply to you; your stage and biomarkers decide which do. The guideline grade, where recorded, says how strong the evidence is.

1.Localised DCIS, breast conservation NCCN category Category 1 (radiotherapy after lumpectomy), NCCN Guidelines: Breast Cancer; SSO-ASTRO-ASCO margin guideline 2016
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).
Lumpectomy (breast-conserving surgery)IMRT / IGRT (modern external beam)Oncotype DX
2.Extensive or multicentric DCISNCCN Guidelines: Breast Cancer
Mastectomy with sentinel node biopsy and optional reconstruction; radiotherapy not needed after mastectomy with clear margins.
Mastectomy Sentinel lymph node biopsy
3.ER-positive DCIS after breast conservation NCCN category Category 1 (tamoxifen); Category 2A (aromatase inhibitor), NSABP B-24, B-35; IBIS-II DCIS; TAM-01
Tamoxifen (or anastrozole in postmenopausal women) for five years to reduce ipsilateral and contralateral breast events; low-dose tamoxifen is an option (TAM-01).
Tamoxifen Endocrine therapy (SERMs, AIs, SERDs)
4.Low-risk DCIS COMET (JAMA 2024)
Active monitoring with mammography every six months and optional endocrine therapy, in trials (COMET, LORIS, LORD) or after shared decision-making where guidelines allow.
Active surveillance Mammography & tomosynthesis Ductal carcinoma in situ (DCIS)Overdiagnosis and false alarms

Every visit

Questions to ask at each visit

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Generated from this cancer's standard of care, biomarkers and open problems. Take the group that matches where you are. To tick, add your own and print, open the one-page appointment sheet.

Newly diagnosed

What is my exact diagnosis, stage, and grade, and which tests established them?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?These results decide eligibility for targeted therapy, immunotherapy, and trials.
Which subtype is my cancer, and does that change the recommended treatment?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?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?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?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?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?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?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?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?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?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?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?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?Open problems are where trials and second opinions matter most.

From day one

Help that costs nothing

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Much of what helps in the first weeks is free if you know to ask: testing, helplines, rides and lodging, second opinions, trial travel.

Any time

What to read next

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Words this page and the cancer page use

In situ: Latin for 'in place': abnormal cells that look like cancer but have not yet broken through the layer they started in.
Ductal carcinoma in situ (DCIS): Breast cancer cells confined inside the milk ducts, found mostly by mammography as calcifications.
Tumour size on a breast report, and why it differs from the scan: The size on the pathology report is the largest continuous lump of invasive cancer measured under the microscope, which is not the same as the size on the mammogram or the MRI.
How ER and PR are scored on a breast report (Allred score, H score, and why PR is not a UK core item): The oestrogen receptor test counts stained nuclei under a microscope and reports a percentage with an intensity, sometimes summarised as an Allred score out of 8 or an H score out of 300.
Partial-breast irradiation: Treating only the part of the breast around where the lump was, instead of the whole breast, on the grounds that almost all recurrences happen there.
Ducts, lobules and the terminal duct lobular unit: The breast is a tree: fifteen to twenty branching duct systems, each ending in a cluster of milk-making sacs called a lobule.
Which staging edition a breast report uses: UICC TNM 8, TNM 9 and the AJCC prognostic stage: UK breast reports stage against the UICC's 8th edition, and the dataset warns against using the American AJCC 8th instead, because the two differ.
Nottingham grade (breast cancer grade 1, 2 and 3): The grade on a breast report is a sum of three scores: how much of the tumour still forms tubes, how ugly its nuclei are, and how many cells are caught dividing.
Lumpectomy (breast-conserving surgery): Removing only the tumour with a rim of normal breast, keeping the breast; almost always followed by radiotherapy.
Carcinoma in situ (CIS): Cancer cells that fill the lining layer where they started but have not broken through the basement membrane into the tissue beneath.

Every term links to the glossary.