Breast cancer health centre

Ductal carcinoma in situ (DCIS)

Ductal carcinoma in situ (DCIS) is the most common type of non-invasive breast cancer.

Ductal means it is cancer that starts in the milk ducts of the breast, in situ means it is in 'its original place' and hasn't developed the ability to spread to breast tissue outside of the ducts.

What is ductal carcinoma in situ?

Ductal carcinoma in situ is an uncontrolled growth of cells within the breast ducts. It is the earliest stage at which breast cancer can be diagnosed. It's sometimes known as stage 0 breast cancer or pre-invasive, non-invasive, ductal intraepithelial neoplasia (DIN) or intra-ductal cancer.

The prognosis for women diagnosed with this type of breast cancer is excellent. The vast majority of cases of ductal carcinoma in situ are curable.

Even though ductal carcinoma in situ is non-invasive, it is imperative that women with the disease receive medical treatment. Experts believe that 1 out of every 3 women with untreated DCIS will later develop invasive breast cancer.

Each year in the UK about 4,800 people are diagnosed with DCIS. Most are women. Fewer than 30 cases of DCIS occur each year in men in the UK.

How is ductal carcinoma in situ diagnosed?

Commonly, ductal carcinoma in situ does not cause the formation of a lump in the breast that can be felt upon examination. About 80% of cases are found by mammograms. Mammograms detect tiny bits of calcium that develop in dead cancer cells. As more and more cancer cells age and die, these calcifications grow. On the mammogram they appear as a shadowy area.

If your mammogram suggests that you may have ductal carcinoma in situ, your doctor may recommend a biopsy. The purpose of the biopsy is to analyse the cells in the suspicious area for cancer and confirm the diagnosis. Biopsies for DCIS are typically done using needles to remove tissue samples from the breast.

After confirming that you have ductal carcinoma in situ, your doctor may recommend other tests. These tests may include an ultrasound or magnetic resonance imaging (MRI) of the breast to gather more information about your cancer. Based on the results of various tests, your doctor will be able to determine the size of your tumour and how much of your breast is involved in the cancer.

How is ductal carcinoma in situ treated?

Your doctor will customise your treatment plan for ductal carcinoma in situ based on your test results and medical history. Among other things your doctor will consider:

• Tumour location
• Tumour size
• Aggressiveness of the cancer cells
• Family history of breast cancer.

Most women with ductal carcinoma in situ do not have the breast removed with a mastectomy. Instead they receive breast-conserving treatment.

The most common course of treatment consists of a lumpectomy followed by radiotherapy. A lumpectomy is a surgical procedure in which a surgeon removes the cancer and a small area of normal tissue around it. The area of normal tissue is taken to make sure all the cancer cells have been removed. Radiotherapy significantly reduces the likelihood that the cancer will come back. Cancer coming back is called recurrence. Radiation can be delivered from an external source to the entire breast. Or it can be given internally to certain areas of the breast.