Ductal Carcinoma In Situ (DCIS)

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This is a condition in which ductal cancer cells grow only inside the ducts of the breast. It is often referred to as a precancerous condition. In situ is a Latin phrase meaning in place, or in this instance, it means the abnormal cells are contained in one place (not spread into other tissue.) DCIS does not always progress to invasive cancer, where the cells invade breast tissue outside the duct. 

DCIS Signs and Symptoms

DCIS is usually found during a mammogram, which may be done as a part of a routine breast cancer screening, or if a woman has a concern about a change she has noticed in the appearance of her breast or felt in her breast. As a result of more women having mammograms regularly, the rate of DCIS being diagnosed has increased dramatically in recent years. DCIS may appear on a mammogram as small clusters of calcifications which have irregular shapes and sizes. 

DCIS doesn't always have signs or symptoms. However, DCIS can sometimes present with:

  • A breast lump
  • Bloody nipple discharge

What Causes DCIS?

 DCIS is known to form as a result of genetic mutations occurring in the DNA of breast duct cells. While these mutations can cause the cells to appear abnormal, the cells are not, as yet able to break out of the breast duct and become invasive.

Researchers can't say for sure what sets off the abnormal cell growth leading to DCIS. It is thought that a number of factors may play a part, including genes passed to you from your parents, your environment and your lifestyle.

Tests Used to Diagnose DCIS

Stages of DCIS

Since DCIS is not an invasive breast cancer, it is not itself a life-threatening condition and is sometimes called Stage 0 cancer. But if left untreated, DCIS can sometimes lead to invasive cancer of the breast. Since it is not currently possible to determine which DCIS cancers will or will not become invasive once diagnosed, they are treated as having the potential to become invasive.

Treatments for DCIS

  • Lumpectomy is the removal of the cancerous lump and a cancer-free margin of tissue. Since the chance of metastasis is so low, lymph node biopsy is not required for diagnosing DCIS, and adjuvant chemotherapy is not necessary for treating it.
  • Simple Mastectomy, the removal of the entire breast, may be necessary if the DCIS area is very large, or if there are a number of areas of DCIS within the breast. ​
  • ​​​Radiation usually follows a lumpectomy as a standard treatment for early-stage breast cancer.
  • Hormonal therapy reduces the risk of a recurrence for women with hormone-receptor-positive DCIS as well as a second primary cancer in the opposite breast.

A Word from Verywell

DCIS, a noninvasive breast cancer, is a perfect example of why it is important to have regular mammograms. It can be identified on a mammogram before it can be felt. As a very early stage breast cancer, it usually doesn't need to be treated with chemotherapy. It usually responds well to treatment and an excellent survival rate.

Edited by: Jean Campbell, MS

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