Discovery and diagnosis: What is ductal carcinoma in situ (DCIS)?
What is ductal carcinoma in situ (DCIS)?
DCIS stands for ductal carcinoma in situ. 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 the breast. DCIS is an early form of breast cancer and may be described as a pre-cancerous, pre-invasive, non-invasive or intraductal cancer. It may affect just one area of the breast, but can be more widespread and affect different areas at the same time.
If DCIS is left untreated, it may, over a period of years, spread into (invade) the breast tissue surrounding the ducts. It is then known as invasive breast cancer. DCIS is not harmful in itself, but it is usually treated to prevent it developing into an invasive breast cancer. Not every woman with DCIS will go on to develop breast cancer if it is left untreated, but it is not possible to predict reliably which women with DCIS will go on to develop invasive breast cancer. Doctors haven’t yet reached a consensus about the nature of this disease and its management, although research is underway to inform this.
Treatment, usually surgical removal of the affected area(s) of the breast, aims to prevent the development of invasive cancer. For most women this will mean removing only a small part of the breast (lumpectomy or wide local excision). However, about four out of ten women (40%) diagnosed with DCIS in the UK have their whole breast removed (mastectomy) because more than one part of the breast is affected (Thornton H, Edwards A, Baum M. Women need better information about routine mammography. BMJ 2003;327:101-3).
There are three grades of DCIS: low, intermediate, and high. The grade relates to how the cells look under the microscope, and gives an idea of how quickly the cells may develop into an invasive cancer (or how likely it is that the DCIS will come back after surgery). Low-grade DCIS has the lowest risk of developing into an invasive cancer, and high-grade carries the greatest risk.
Most women with DCIS have no signs or symptoms and only know they have it when it is seen on a mammogram. This is why DCIS has been diagnosed more frequently since three-yearly breast screening for women aged 47-73 was introduced by the UK National Health Service (NHS).
DCIS usually shows up on a mammogram as an area where tiny specks of calcium have collected in the breast ducts, known as
micro-calcification. It is important to remember that most micro-calcification is not DCIS or cancer. A few women with DCIS, however, do have symptoms, such as a breast lump, fluid (discharge) coming out of the nipple, or
a type of rash involving the nipple called Paget’s disease (see Diagnostic mammograms and Macmillan Cancer Support ).
In the UK, non- invasive cancers such as DCIS account for one in five cancers (20%) detected by breast screening; that's around two thousand women a year (NHS Breast Screening Programme). Only one of the women we spoke with had ever heard of DCIS before her own diagnosis. Many were unsure as to whether it was actually cancerous or not. Most wanted more information about DCIS and felt unprepared for the diagnosis because they’d had no symptoms. With hindsight, a few women wondered if they had actually had a symptom but one which hadn’t been noticeable enough for them to visit their GP.
Last reviewed November 2011.
Last updated November 2011.
