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Learning About Ductal Carcinoma in Situ (DCIS)

Milk ducts of the breast, with details showing location and structure

What is DCIS?

Ductal carcinoma in situ (DCIS) is the growth of abnormal cells in the milk ducts of the breast. It's a very early form of non-invasive breast cancer. Non-invasive means that the cells haven't spread. Some cases of DCIS will become invasive breast cancer, but it's impossible to know which ones.

What causes it?

The exact cause of DCIS isn't known. Getting older and being female may play a part.

What are the symptoms?

Most of the time, DCIS doesn't cause symptoms. But in some cases, symptoms can include a lump in the breast or fluid or blood coming from the nipple.

How is it diagnosed?

DCIS is usually found during a mammogram, where it may look like a pattern of white areas or bits of calcium (calcifications). To diagnose DCIS, your doctor will remove a sample of breast tissue and look at it under a microscope. This is called a breast biopsy.

How is it treated?

The main treatment for DCIS is:

The choices are:
  • Breast-conserving surgery. This removes just the cancer and a border of healthy tissue around it.
  • Mastectomy. This removes the whole breast. Nearby tissue may also be removed and checked for cancer cells.

Other treatments may include:

Radiation therapy.
This uses high-dose X-rays to destroy cancer cells and shrink tumours. Radiation may be given after surgery.
Endocrine therapy.
These medicines block hormones that cause certain cancers to grow. This helps slow or stop cancer growth.

Clinical trials are being done to find out if other treatments are an option for some people with DCIS. Talk to your doctor if you're interested in a clinical trial.

Your doctor will talk with you about your options and then make a treatment plan.

Follow-up care is a key part of your treatment and safety. Be sure to make and go to all appointments, and call your doctor or nurse advice line (811 in most provinces and territories) if you are having problems. It's also a good idea to know your test results and keep a list of the medicines you take.

Where can you learn more?

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