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What is ductal carcinoma in situ (DCIS)?

Ductal carcinoma in situ (DCIS) is the name for abnormal changes in the cells in the milk ducts of the breast. 'In situ' means 'in place'. DCIS is a non-invasive breast cancer. The abnormal cells are contained inside the milk ducts.

What’s the difference between DCIS and invasive breast cancer?

The abnormal cells seen in DCIS are cancer cells. However, DCIS is not breast cancer as we commonly understand it. In breast cancer, the cancer cells have spread out of the milk ducts into the surrounding breast tissue. That is why it’s sometimes called ‘invasive’ breast cancer. A woman cannot die from DCIS unless it develops into invasive breast cancer.
 

Illustration of a woman's breast, showing DCIS and invasive breast cancer
Illustration of a woman's breast, showing DCIS and invasive breast cancer

How common is DCIS?

About 1200 women are diagnosed with DCIS each year in Australia.

DCIS can be found in women at any age. However, most women are between 50 and 59 years old when their DCIS is found. DCIS can also develop in men although this is very rare.
 

What are the symptoms of DCIS?

DCIS cannot usually be felt as a breast lump or other breast change.

Most cases of DCIS are found following routine screening with mammograms. DCIS often appears as small flecks of calcium (called microcalcifications) on a mammogram or ultrasound.

Most women with DCIS are not aware of any symptoms at the time of diagnosis.
 

Why is DCIS treated?

The aim of treating DCIS is to prevent invasive breast cancer from developing. If DCIS is not treated it may develop into invasive breast cancer, which can spread outside the ducts into the breast tissue and then possibly to other parts of the body.

We don’t know for certain how many women with DCIS would develop invasive breast cancer if they were not treated. Also, it is not possible to predict which women with DCIS will develop invasive breast cancer if they were not treated or how long after the diagnosis of DCIS an invasive breast cancer would develop. Some women with DCIS may never develop any problems if they are not treated. However, some women with DCIS may develop invasive breast cancer.

Because DCIS may develop into invasive breast cancer and invasive breast cancer can spread and cause death, women with DCIS are generally recommended to have treatment. Treatment for DCIS aims to help prevent invasive breast cancer from developing and DCIS from coming back in the breast.

DCIS can be treated successfully and most women diagnosed and treated for DCIS will not later develop invasive breast cancer.

A focus of current research effort is to identify whether treatment for DCIS can vary dependent on the grade of the disease. There are currently two international clinical trials, (the LORIS trial and the LORD trial) that are investigating the “watch and wait” approach compared to immediate treatment for the management of low-grade DCIS. The LORIS trial is currently recruiting patients in the United Kingdom and the LORD trial is planned to soon start recruiting patients in Europe. The results from these trials will help to determine the best treatment options for women with low-grade DCIS. At this time, however, there are no national or international guidelines which recommend a “watch and wait” management option for low-grade DCIS.


Find out more about:

  • Treatments for DCIS
  • The LORIS Trial: a phase III trial of surgery versus active monitoring for low risk DCIS
  • The LORD (LOw Risk DCIS) study: a phase III trial aiming to determine whether screen-detected low-grade DCIS can safely be managed by an active surveillance strategy or that the conventional treatment should remain the standard of care.