Breast Screening
What is ductal carcinoma in situ (DCIS)?
Ductal carcinoma in situ (DCIS) is referred to as an early form of breast cancer.
It may also be described as a pre-cancerous, pre-invasive, non-invasive, or intraductal cancer. This means the cancer cells are inside the milk ducts, or 'in situ' (in place), and have not developed the ability to spread either within or outside of the breast.
Most people with DCIS have no signs or symptoms, so it is mostly found through breast screening after having a mammogram. This is why DCIS has been diagnosed more frequently since 3-yearly breast screening was introduced on the UK National Health Service breast screening programme (NHS BSP).
With DCIS, a mammogram shows a cluster of small white dots. These white dots contain calcium and are known as micro-calcifications. They are generally too small to be felt. Most micro-calcifications turn out not to be DCIS (see 'Benign breast problems').
A few women with DCIS do have symptoms. They may have a lump, a discharge from the nipple, or, rarely, a type of rash involving the nipple called Paget's disease.
If DCIS is left untreated, it may, over a period of years, begin to spread into (invade) the breast tissue surrounding the ducts. It is then known as invasive breast cancer.
DCIS is the most common kind of non-invasive breast cancer and there are different grades, including low, intermediate and high. This grading is based on what the cells look like under the microscope. Low-grade DCIS has the lowest risk of developing into invasive cancer and high-grade the greatest risk.
DCIS is not harmful in itself, but it is usually treated to prevent it from developing into an invasive breast cancer. Not every person with DCIS will go on to develop breast cancer if it is left untreated, but it is not possible to predict reliably which people with DCIS will go on to develop invasive breast cancer.
Treatment for DCIS
Treatment, which is usually surgical removal of the affected area(s) of the breast, aims to prevent the development of invasive cancer.
For most people, treatment will mean removing only a small part of the breast with a lumpectomy or wide local excision. However, some people diagnosed with DCIS in the UK have their whole breast removed because more than one part of the breast is affected (see mastectomy for DCIS).
In the UK, non-invasive cancers such as DCIS account for around 1 in 5 cancers (20%) that are detected by breast screening: this number is compared to 4 in 5 breast cancers being diagnosed as invasive (NHS Breast Screening: ‘helping you decide’, 25 February 2025).
Health professionals haven't yet reached a consensus about the nature of the disease and its management, though research is underway to inform this.
Experiences with DCIS diagnosis
Because DCIS has an uncertain natural progression, most women we spoke with found it hard to understand. None of the women we interviewed who had had DCIS had heard of it before.
Many were confused as to whether it was actually cancerous or not. Most wanted more information about DCIS, and many felt unprepared for the diagnosis because they'd had no symptoms.
Had not heard of DCIS before she was told she had it.
Had not heard of DCIS before she was told she had it.
So we went off to the hospital which was some distance away and still no problems and there was the same radiographer that I saw at the mobile unit and she showed me what they were looking at and she just called it 'chalk'. That's all I knew.
And then I had to wait and see the consultant radiologist and he did an ultrasound and then said, mentioned pre-cancerous cells and said "we'll do a biopsy and we can do it now" and I just thought "Bloody hell they're looking for cancer" [laughs].
So I phoned up NHS direct, phoned up Breast Cancer Care, only knew it was called 'chalk', had no other information. Oh and they'd mentioned calcifications, so that was the only thing I could mention.
Because I'd been, heard about pre-cancerous cells my husband did ask him if it was something leading up to cancer or cancer and he said it was cancer. They took us to see the breast care sister and she gave us a piece of paper with 'DCIS' on. That was it. That was all we knew. And we had to make a decision [about when to have the mastectomy] based on that.
Had not heard of DCIS before her own diagnosis.
Had not heard of DCIS before her own diagnosis.
The day that we received the results I was told that I had DCIS and they explained very briefly what it was.
Had not heard of DCIS before and got contradictory information about it being cancerous.
Had not heard of DCIS before and got contradictory information about it being cancerous.
It was ok. Th kept lying to me. I mean I didn't really understand what I had. They told me it was a ductal carcinoma in situ. It was pre-malignant, it wasn't cancer, it was nothing. It was treated like it was nothing and it only occurred to me much later "why did they take away half my breast for nothing".
I looked it up eventually on the internet. I got a computer, this was a long time ago so not everybody had a computer, but I got a computer, looked it up, looked up DCIS and I found 'malignant condition'. Oh yes, I forgot to tell you that I saw the Oncologist just after my wide excision. And he said "do you know what you've had" and I said "yes, I've had DCIS but it wasn't malignant" and he said to me "of course it was malignant, who on earth told you it wasn't malignant?" And I said "the Surgeon". He replied "no he didn't". Which didn't make me feel exactly great because I wasn't lying. So I had these mixed messages of "it's not malignant", "yes it is malignant". I actually learned it was malignant from the Oncologist and I think that was another reason why I really thought "I need extra information to find out what is it? What is DCIS? What have I had?"
See more about women's experiences of DCIS here.
See also ‘DCIS: views on breast screening’, ‘Invasive breast cancer’, and our section on DCIS for more information.
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