Ductal carcinoma in situ (DCIS)

DCIS is an early form of breast cancer, where the cancer cells have developed within the milk ducts but remain there ‘in situ’ having not yet developed the ability to spread outside the ducts into the surrounding breast tissue or to other parts of the body.

You may hear DCIS described as a pre-invasive, intraductal or non-invasive cancer. Occasionally you may also hear it incorrectly described as pre cancerous. Both men and women can develop DCIS, however it is very rare in men. As a result of being confined to the breast ducts, a diagnosis of DCIS has a very good prognosis (outlook).


Most people with DCIS have no symptoms. However, some people may notice a change in the breast such as a lump, discharge from the nipple or more rarely, a type of rash involving the nipple known as Paget’s disease of the breast.


As DCIS tends not to produce symptoms, most people only find out they have it when it is seen on a mammogram (breast x-ray). This is why DCIS has been diagnosed more frequently since routine breast screening was introduced. It accounts for approximately 20% of breast cancers that are diagnosed by screening mammograms.

DCIS may be present in the breast if small white dots are seen on the mammogram. These white dots are small spots of calcium salts and are known as microcalcifications. However, not all areas of microcalcification are found to be DCIS, and many women develop benign (not cancer) calcifications in their breasts naturally as the breast tissue ages.

If you have symptoms such as a lump or nipple discharge, tests including a clinical (breast) examination, a mammogram, and/or ultrasound scan, and a core biopsy and/or fine needle aspiration (FNA) may be carried out. Together these investigations are known as triple assessment.

If you do not have any symptoms, but calcifications are present on the mammogram you may have a stereotactic core biopsy.

The samples taken are x-rayed to ensure they contain the microcalcifications before being sent to the laboratory where they are examined under a microscope to establish a diagnosis.

Are there different types (grades) of DCIS?

DCIS is graded based on what the cells look like under the microscope. A system is used to classify cancer cells according to how different they are to normal breast cells and how quickly they appear to be growing. It can be graded as high, intermediate or low grade DCIS.

If DCIS is left untreated, the cancer cells may eventually develop the ability to spread outside the ducts into the surrounding breast tissue or to other parts of the body. This is known as invasive ductal breast cancer. It is thought that high-grade DCIS is more likely to become an invasive ductal breast cancer than low-grade DCIS.

Find out more about how DCIS is treated.

Last reviewed: May 2015
Next planned review begins 2017

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