DCIS, stage 0

What DCIS is

DCIS, ductal carcinoma in situ, is breast cancer at its earliest possible point. The abnormal cells are inside the milk ducts and have not grown through the duct wall. Because they have not, they cannot reach the lymph nodes or the rest of the body. It is nearly always found on a mammogram as a cluster of tiny calcifications rather than felt as a lump. It is treated to stop it from becoming an invasive cancer later, and treatment succeeds at that for the great majority of people.

What usually happens next with DCIS, in order

1. Measuring it. The extent on the mammogram matters more than for most cancers, because it decides whether a lumpectomy can remove all of it with a clear edge. Sometimes an MRI is added.
2. Surgery. A lumpectomy if the area is small enough relative to the breast, or a mastectomy if it is widespread or if you prefer it. For DCIS the pathologist wants a margin of at least 2 millimeters of normal tissue around it, and a second operation to widen the margin is sometimes needed.
3. Lymph nodes. Not usually checked with a lumpectomy, because DCIS does not spread to them. Dr. Perkins does not usually do a sentinel node biopsy at the time of a mastectomy either. Instead a tracer can be placed that maps the lymph nodes, so that the nodes can still be checked later if invasive cancer turns up on the final pathology report. Not every surgeon works this way, so ask yours what is planned for you.
4. Radiation. Usually recommended after a lumpectomy, to lower the chance of DCIS or invasive cancer returning in that breast. For some small, low-grade DCIS it may be reasonable to skip it. Not needed after a mastectomy.
5. An anti-estrogen pill. If the DCIS is estrogen receptor positive, five years of tamoxifen or an aromatase inhibitor may be offered. It lowers the chance of a new cancer in either breast. It is optional, and many people weigh it against side effects.

Chemotherapy is not used for DCIS, and HER2 testing is not usually done on it.

Choices you will be asked about with DCIS

Lumpectomy plus radiation, or mastectomy. For those who have the choice, the chance of the cancer coming back somewhere else in the body is the same either way. Whether to take the pill afterward. If a mastectomy, whether to reconstruct, and when.

Questions to bring to your appointment

These are built for DCIS. The report decoder narrows the list further from your own report, and the print button there puts it on paper with room to write. Bring someone with you if you can; two sets of ears hear more than one.

• How large is the area of DCIS on imaging, and what grade is it?
• Am I a candidate for a lumpectomy, and would you recommend radiation afterward?
• Will the lymph nodes be checked, and why or why not?
• Would an anti-estrogen pill be worth taking afterward, and what are the trade-offs?
• How likely is it that the final report after surgery shows an invasive cancer as well?
• If I want to talk to a plastic surgeon before deciding, can that happen first?
• Is there a clinical trial I should know about?
• How much time do I have to decide? Is there anything that must be decided today?
• Who is my contact between appointments, and how do I reach them?
• Is there a nurse navigator or counselor I can be connected with?

Where this comes from

Published 7 September 2026 as part of the guide; a page of its own since 9 September 2026; reviewed by Dr. Perkins 13 September 2026, whose own wording on lymph nodes and on how she treats DCIS was added the same day and revised by her on 14 September 2026.