Canadian Cancer Society logo

Breast cancer

You are here: 

Ductal carcinoma in situ (DCIS)

With ductal carcinoma in situ (DCIS), cancer cells are found only in the lining of the breast duct and have not spread outside the duct into nearby breast tissue or to other organs in the body.

DCIS is the most common type of non-invasive breast cancer. It may also be called intraductal carcinoma or non-invasive ductal carcinoma. Nearly all women diagnosed with this early stage of breast cancer can be successfully treated.

DCIS is generally too small to be felt during a clinical breast exam (CBE). It is most commonly found by mammography, where it appears as microcalcifications.

Women with DCIS have an increased risk of developing an invasive ductal carcinoma. However, it is not yet known how to identify which DCIS will progress to an invasive cancer, and which will not.

DCIS may be classified based on what the cells look like when viewed under the microscope. There are 2 main subtypes of DCIS: comedo and non-comedo.

Comedo

The term comedo is used to describe the appearance of DCIS cells. When examined under a microscope, the cells have dead material (necrosis) that plugs the middle. This material can be squeezed or expressed out of the cells, like a blackhead (comedo) on the skin.

Comedo DCIS tends to grow quickly and spread into surrounding breast tissue.

Non-comedo

Non-comedo DCIS grows more slowly than the comedo type of DCIS, and is less likely spread into the surrounding breast tissue.

There 3 are different types of non-comedo DCIS:

  • solid DCIS
    • The cancer cells completely fill the breast duct(s).
  • cribiform DCIS
    • There are spaces and gaps in between the cancer cells and the ducts are not filled completely.
  • papillary and micropapillary DCIS
    • The cells are arranged in a fern- or feather-like (papillae) pattern towards the centre of the breast duct.
    • In micropapillary DCIS, the papillae are smaller than the papillae in papillary DCIS.

Stories

Researcher Dr Ming-Sound Tsao Dr Ming-Sound Tsao created a realistic lab model of lung cancer.

Learn more

Clinical trial discovery improves quality of life

Illustration of test tubes

A clinical trial led by the Society’s NCIC Clinical Trials group found that men with prostate cancer who are treated with intermittent courses of hormone therapy live as long as those receiving continuous therapy.

Learn more