What is DCIS: Stage 0 Breast Cancer
Ductal Carcinoma in Situ (DCIS) is Stage 0 breast cancer. It is the earliest stage that breast cancer can be detected. This post will share some information about DCIS and offer links to resources to get more information.
Please Note: I am not a doctor or medical professional. This article is written from my patient perspective. Always consult your doctors for medical advice. See my disclaimer for more information.
My Story
I was diagnosed with DCIS in the fall of 2019 after an abnormal mammogram and a mammogram-guided biopsy. Before my diagnosis, I didn’t know much about the staging or types of breast cancer. That changed once I got my diagnosis!
I began to do extensive research on DCIS to figure out what it was and what treatment options would be appropriate for me. The more I discovered, the more thankful I got that the mammogram had picked it up so early. My mammogram showed the calcifications clearly, which enabled treatment to be as minimally invasive as possible.
My DCIS was caught before a lump had formed. It was able to be removed with a lumpectomy, and I followed that up with radiation to address any potential spots of DCIS that were too small to be caught by imaging.
This post will help you understand what DCIS is and point you to some great resources to find more information out about Stage 0 breast cancer.
Cancer Staging and How DCIS Fits In
First, we need to discuss how DCIS fits into the current cancer staging system.
All cancers, no matter what type, are staged and given a number. These numbers range from 0-IV (0-4). Stage IV cancers have become metastatic or have spread to other locations in the body. At this stage, cancer can be considered terminal.
Stage IV breast cancer is also called metastatic breast cancer, or MBC. There are treatments available to help slow the progression of MBC and prolong life for patients. Unfortunately, at this time, MBC is not curable.
If you have read in the news or know someone who has died of breast cancer, it is highly likely that person died of metastatic breast cancer.
Cancer Staging Changes in 2018
Researchers continue to gather more information about the biology of cancer and how it spreads. In 2018 a change was made to how cancer is staged.
Cancer staging identifies where the cancer is in the body and how much of it there is. Staging helps doctors have a shared language to discuss cancer and plan treatment.
Cancer Staging Before 2018
Before 2018, cancer staging included less information about the tumor than it does now.
Pre 2018 staging included information about the physical characteristics of the tumor but didn’t take into account any additional information about the biology of the cancer.
- T- Tumor Size
- N- Lymph node status
- M- Metastases (whether it has spread to other parts of the body
These three pieces of information are combined to determine a cancer stage between 0-IV.
Cancer Staging After 2018
After 2018, breast cancer staging was updated to include information about hormone receptor status. This additional information allows doctors to customize treatments more precisely for specific types of breast cancer.
Post-2018 Staging includes TNM status (see above) but also adds in
Tumor Grade– How much the cells look like cancer
- Grade 1– Cells look Mostly normal and are slow-growing
- Grade 2– Middle of the road with about half cancer and half regular
- Grade 3– Cells look most abnormal and are faster growing
Hormone Receptor Status– Each one can be positive or negative
- ER– Estrogen receptor
- PR– Progesterone Receptor
- HER2 Status – HER2 is a protein on the outside of all breast cells. If a tumor is HER2 positive, it will grow faster
Stage 0 Breast Cancer
DCIS is considered Stage 0 breast cancer. On a pathology report, DCIS is reported as Tis (tumor in situ).
There isn’t a change in the staging of DCIS depending on the size of the tumor. However, tumor size is one of the factors that goes into the staging of invasive breast cancers.
DCIS can be located in one location of the breast, or it can be found in many different areas of the breast. In that case, it is usually called multi-focal.
What do the Letters in DCIS Mean?
Each letter in DCIS offers us the ability to understand this type of early-stage breast cancer.
D: Ductal
The D refers to the location of the cancer. In the case of DCIS, the tumor is located inside the milk ducts of the breast. Breast cancer is most typically found here, but cancer can be found in the tissue (inflammatory), nipple (Paget’s), or lobules. The links that I have included down below will have many excellent diagrams and information to better inform you about the types and locations of cancer in the breast.
C: Carcinoma
A Carcinoma is a type of cancer that starts in the skin or the tissue linings of our organs .Other types of cancer that begin in the brain or blood, for example, aren’t considered carcinomas.
IS: in Situ
This is a Latin term that means “in place.” If there was any good news about DCIS, this is where it is found. DCIS hasn’t broken out of the milk ducts, invaded the surrounding tissue, or spread to the lymph nodes. It is possible to have DCIS and have a small amount of invasion. If so, sometimes that is called a “micro-invasion.”
Is DCIS Cancer?
Short Answer: Yes
Longer Answer: DCIS is the earliest form of cancer. It has been called a “pre-cancer” in some circles, but that language is being replaced gradually with language that is more in line with current staging. Other language includes “pre-invasive” or “non-invasive.”
I like this blog article written by another DCIS patient, Ricki Lewis, that emphasizes how important it is to call DCIS cancer.
Why does DCIS Need to Be Removed?
At the time of this writing, doctors don’t know which instances of DCIS will turn into invasive breast cancer. Some DCIS might stay entirely in place and never pose a threat. However, some DCIS will grow and spread. If it isn’t removed and spreads, the patient will need more aggressive treatments.
There is currently a study going on to evaluate whether active surveillance would be appropriate for DCIS patients. If you would like to follow the progress of the COMET study, I have included the link here.
During my research about DCIS, I came across many sources of information to help me better understand this type of cancer. I have included links below so that you can be more informed about the different types and stages of breast cancer.
In a future post, I plan to discuss the various treatment options available for patients with DCIS. I’ll link to it once it is live.
Have any questions? Feel free to comment below.
References and Resources for Further Study
- Patient Book by NCCN
- Stages of Breast Cancer
- Types of treatment
- Benign breast Conditions
- Guide to Pathology report:
- Breast Cancer 360 Overview
- DCIS myths
- Pathology
- Staging before 2018
- Staging after 2018
Jennifer Douglas
Jennifer is the author of "A Breast Cancer Journey: Living it One Step at a Time," breast cancer survivor, and patient advocate. Her book, published in 2023 by Bold Story Press, is an encouraging guide for breast cancer patients. It contains first-hand information, organized by topics, to help readers navigate the diagnosis, treatment, and recovery from breast cancer. Her writing emphasizes emotional, mental, and physical well-being along with empowered decision-making.
Thank you for the clear explanation of DCIS. I was just diagnosed 4/27/21. Met with surgeon and have appointment with radiation and oncology next week. Trying to learn as much as I can.
I hope that your appointments go well and that you’re able to get a plan in place for the treatment. Keep me posted and best wishes during your treatment!!
Thank you for this article. It is very clear and understandable. I am having a lumpectomy Sept.21st. Follow up with oncologist 2 weeks later.
Kathy, I’m so glad it was clear and helpful. I hope your surgery goes smoothly! Wishing you peace and calm as you head towards your lumpectomy.