The first 60 days: 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 would become invasive if left. Lumpectomy with radiotherapy, or mastectomy, halves local recurrence, so the live question is which low-risk DCIS can safely be watched: the COMET trial (2024) found active monitoring no worse at two years. Below, week by week, is what OnCo's record of Ductal carcinoma in situ (DCIS) says about the first two months: the order is typical, the timing is yours to ask about. Sections appear only where the record has something to say. Orientation, not medical advice.
What happens now
Staging tests establish exactly what and where the cancer is. Everything else follows from the answers.
Ask which of these were tested and what the results were; see the report reader for what each value means.
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.
- PathologistNamed in the standard of care for: Localised DCIS, breast conservation, Extensive or multicentric DCIS, Low-risk DCIS.
- RadiologistNamed in the standard of care for: Low-risk DCIS.
- SurgeonNamed in the standard of care for: Localised DCIS, breast conservation, Extensive or multicentric DCIS, Low-risk DCIS.
- Medical oncologistNamed in the standard of care for: Localised DCIS, breast conservation, Extensive or multicentric DCIS, ER-positive DCIS after breast conservation, Low-risk DCIS.
- Clinical oncologist (radiotherapy)Named in the standard of care for: Localised DCIS, breast conservation, Extensive or multicentric DCIS.
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.
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 conservationNCCN 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).
Mastectomy with sentinel node biopsy and optional reconstruction; radiotherapy not needed after mastectomy with clear margins.
- 3.ER-positive DCIS after breast conservationNCCN 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).
Active monitoring with mammography every six months and optional endocrine therapy, in trials (COMET, LORIS, LORD) or after shared decision-making where guidelines allow.
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.
Much of what helps in the first weeks is free if you know to ask: testing, helplines, rides and lodging, second opinions, trial travel.
- Ductal carcinoma in situ (DCIS): the full pageDCIS is abnormal cells confined to the milk ducts; it is not yet invasive cancer and cannot spread, but some would become invasive if left. Lumpectomy with radiotherapy, or mastectomy, halves local recurrence, so the live question is which low-risk DCIS can safely be watched: the COMET trial (2024) found active monitoring no worse at two years.
- One-page appointment sheetYour questions, the words you may hear, what to bring, and space for the answers. Print it.
- Treatment sequencingWhich treatment tends to follow which, line by line.
- NavigatorStandard of care for your stage, what you have tried, and trials near you.
- 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.
- 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.
- Mastectomy: Removing the whole breast, either for cancer or preventively in BRCA1/2 carriers, where bilateral risk-reducing mastectomy cuts breast cancer risk by 90% or more.
Every term links to the glossary.