Ductal carcinoma in situ (DCIS)

People with DCIS do not usually have any symptoms. Most cases are diagnosed from a mammogram (X-ray of the breast).

The mammogram shows a cluster of small white dots. These white dots contain calcium and are known as microcalcifications. 

Not all areas of breast tissue containing microcalcifications turn out to be DCIS. To check if it is DCIS, a biopsy will be taken. This is when a piece of breast tissue is removed using a needle.

The breast tissue removed during the biopsy will be looked at under a microscope. If the biopsy shows you have DCIS, you will be referred for treatment.

There are different types of DCIS. They can be divided into:

• Low-grade
• Intermediate
• High-grade

These grades are based on what the cells look like under the microscope. If DCIS is left untreated, the cells may spread from the ducts into the surrounding breast tissue and become an invasive cancer. This means that they can spread to other parts of the body.

It is thought that low-grade DCIS is less likely to become an invasive cancer than high-grade DCIS.

Treatment aims to remove the early cancer cells, to avoid them developing into an invasive cancer (a cancer that spreads beyond the milk ducts).

Surgery is the main treatment for DCIS. During surgery, some or all of your breast will be removed. How much is removed will depend on how much of your breast is affected.

There are two main options:

• Wide local excision (lumpectomy): This means removing a piece of the breast containing the DCIS. Your surgeon will also remove an area of normal tissue around the area of DCIS.
• Mastectomy: This is the removal of your whole breast. This may be done if the DCIS is in a number of different parts of your breast or if it covers a very large area.

Sometimes your surgeon may also remove some lymph nodes from your armpits during surgery, to see if the cancer has spread outside the breast. This is called a sentinel lymph node biopsy. People who have a mastectomy usually have this type of biopsy done during the operation. People having wide local excision surgery may not need this type of biopsy. Read more about sentinel lymph node biopsies here.