Ductal Carcinoma in Situ (DCIS)

Figure 1

What is Ductal Carcinoma in Situ?

A diagnosis of Ductal Carcinoma in Situ (DCIS) can cause confusion amongst some women, as it is often described as a pre-invasive or pre-cancerous disease. As a result, some women diagnosed with DCIS may consider that they do not have breast cancer.

A diagnosis of DCIS means that some cancerous cells are contained within the milk ducts of the breast (the pathway through which milk travels to the nipple).

DCIS is not breast cancer as we commonly understand it, because it is a non-invasive breast cancer. This means that while the cancerous cells look abnormal and divide in an abnormal way, they do not have enough gene faults or gene mutations to allow them to spread outside the ducts to the surrounding breast tissue to become invasive (early breast cancer) or to spread anywhere else in the body (to become secondary breast cancer). Essentially the cancer cells are completely contained within the milk ducts (see figure 1).

DCIS isn't life threatening in itself, but having DCIS may increase the risk of developing invasive (early breast cancer) later in life.

Approximately 1,600 women each year in Australia are diagnosed with DCIS1, and it accounts for up to one fifth of all breast cancers.

How is DCIS diagnosed?

Most women with DCIS do not show any signs or symptoms, as DCIS usually does not appear as a breast lump or other breast change.

DCIS is commonly diagnosed through a mammogram or ultrasound, however a biopsy is also required to confirm whether DCIS is present.

A pathologist will usually attribute a grade to DCIS, which indicates the patterns of cancer cell growth and how fast the cancer cells are growing. Based on what the DCIS cancer cells look like under a microscope, DCIS can be graded as high, intermediate or low grade.

High grade DCIS is very likely to develop into invasive breast cancer if left untreated. Low or intermediate grades of DCIS may simply remain as such for many years. However, in some cases low or intermediate grade DCIS may develop into invasive breast cancer. 

While the size and grade of DCIS can help predict if it will become invasive, unfortunately it is not possible to know for certain if a woman will go on to develop invasive breast cancer.

I have DCIS -- will I develop invasive (early) breast cancer in the future?

If you have been diagnosed with DCIS, your risk of developing invasive (early) breast cancer is increased.

Results from a recent Australian study found that between 1995 and 2005, 13,749 women were diagnosed with DCIS and that, by the end of 2005, 706 of those women had developed invasive breast cancer even though they had received treatment for DCIS.2

Essentially this study found that women who have been diagnosed with DCIS are, on average, 3.9 times more likely to develop invasive breast cancer than Australian women of a similar age who have not had DCIS.

However it is important to recognise that not every woman with DCIS will develop invasive breast cancer.

"I was diagnosed with DCIS at age 35. Three months after completing my radiotherapy treatment, I fell pregnant with my third child. There really is life after DCIS!" --Woman, aged 48

Treatment for DCIS

As it is not possible to determine which women may go on to develop invasive breast cancer after a diagnosis of DCIS, women with DCIS are usually recommended to undergo treatment.

The goal of treating DCIS is to help prevent it from returning to the breast and to help ensure that it does not progress to invasive breast cancer.

"Nearly 10 years later, fit, well, busy and enjoying life, I am grateful that my breast cancer was DCIS.  As I said at a recent talk I gave about breast cancer, I've been there, done that -- the cancer has been and gone!" --Woman, aged 71

Treatment usually consists of breast conserving surgery, also called lumpectomy, partial mastectomy or wide local incision (which may or may not be followed by radiotherapy); or a mastectomy.

Generally it is not recommended to have lymph node removal for DCIS, however if DCIS is extensive, and you require a mastectomy, or if your surgeon is unsure about the presence of invasive breast cancer, you may be offered a sentinel node biopsy.

While some women may undergo chemotherapy, it is generally not used to treat DCIS after surgery.

However, if DCIS is oestrogen receptor positive (which means that the cancer needs oestrogen to grow), oestrogen blocking treatments such as Tamoxifen or an aromatase inhibitor (such as letrozole, anastrozole or exemestane) may be recommended.

  1. Australian Institute of Health and Welfare & National Breast and Ovarian Cancer Centre 2010. Risk of invasive breast cancer in women diagnosed with ductal carcinoma in situ in Australia between 1995 and 2005. Cancer series no. 51. Cat. no. CAN 47. Canberra: AIHW.
  2. Australian Institute of Health and Welfare & National Breast and Ovarian Cancer Centre 2010. Risk of invasive breast cancer in women diagnosed with ductal carcinoma in situ in Australia between 1995 and 2005. Cancer series no. 51. Cat. no. CAN 47. Canberra: AIHW

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