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.


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 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.


Rebecca and James Hamm It was very important that the fundraiser be in honour of my uncle, because it’s a great way to show our support for him.

Read the Hamm's story

A helping hand for families

Illustration of crowd

The Canadian Cancer Society helps with expenses for children in cancer treatment and their families.

Learn more