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Ductal carcinoma in situ (DCIS, stage 0)
Hearing the word 'cancer' with DCIS can be confusing and scary. The reassuring part: DCIS hasn't spread outside the milk ducts, and treatment aims to keep it from ever becoming invasive.
ℹ️ General information to help you and your loved ones talk with your care team, not medical advice. Read our disclaimer.
The quick guide
What it means: Abnormal cells are inside the milk ducts and haven't grown into nearby breast tissue. It's called stage 0 or 'pre-invasive.'
How it's found: Usually found on a screening mammogram, then confirmed with a biopsy. ER status is checked too.
How common it is: About 1 in 5 new breast cancer diagnoses in the US is DCIS.
How treatment works
🌱 Early-stage
- Lumpectomy, usually followed by radiation; or mastectomy for larger areas.
- For ER-positive DCIS, tamoxifen or an aromatase inhibitor may be offered to lower the risk of a future breast cancer.
- Some people with small, low-risk DCIS discuss skipping radiation with their team.
🔁 Advanced or metastatic
- DCIS doesn't spread. If it comes back as invasive cancer, it's treated like invasive breast cancer.
Approvals depend on stage and prior treatment. Your care team will decide what fits you.
Drug guides
Biomarker tests that matter
Side effects you may notice
❓ Questions you and your loved ones can ask
- How large is the DCIS and what grade is it?
- Do I need radiation after lumpectomy?
- Should I take hormone therapy to lower my risk?
Back to Breast cancer overview. Other types: Hormone receptor-positive (HR+/HER2-) breast cancer, HER2-positive breast cancer (and HER2-low), Triple-negative breast cancer (TNBC), Inflammatory breast cancer (IBC).
Written by the Cancer Side Effects Guide team from FDA labels and leading cancer centers. Not medical advice. · Last updated: October 15, 2026 · How we write