An Overview of Ductal Carcinoma In Situ (DCIS)

Ductal carcinoma in situ (DCIS) is a condition in which cancer cells only grow inside the ducts of the breast. It is often referred to as a precancerous (stage 0) condition or an early stage breast cancer. In situ is a Latin phrase meaning "in place;" in this instance, it means the abnormal cells are contained in this part of the breast, not spread to other tissue. DCIS does not always progress to invasive cancer, where the cells invade breast tissue outside the duct. 

Signs and Symptoms

According to the American Cancer Society, one in five new breast cancers will be DCIS. Nearly all of the women who develop early breast cancer are cured. 

DCIS doesn't always have signs or symptoms. When it does, they can include:

• A breast lump
• Puckered or unusual looking skin
• Thickened areas below the skin
• Nipple discharge

It is good idea to make an appointment with your healthcare provider if you notice breast changes.

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Causes and Risk Factors

DCIS is known to form as a result of genetic mutations in the DNA of breast duct cells. While these mutations can cause the cells to appear abnormal, they are not because they have not been able to break out of the 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 your genes, environment, and lifestyle.

Certain factors may increase your risk for DCIS, including:

• Increasing age
• Personal history of benign breast disease, including atypical hyperplasia, a precancerous condition that causes accumulation of abnormal cells in the breast
• Family history of breast cancer
• Having never been pregnant
• Having a first period before age 12
• Starting menopause after age 55
• Certain genetic mutations, including BRCA1 and BRCA2

Diagnosis

DCIS is usually found during a mammogram, which may be done as a part of a routine breast cancer screening, or if you have a concern about a change in the appearance or feel of your breast. As a result of more women having mammograms regularly, the rate of DCIS being diagnosed has increased dramatically in recent years.

DCIS appears as bright white specks (microcalcifications) on a mammogram. They are seen in clusters and have irregular shaping and size. If the radiologist suspects DCIS, a diagnostic mammogram is done, which offers a better view of the breast. The diagnostic mammogram looks more closely at microcalcifications to determine whether there is a reason for concern.

If an area needs further evaluation, a core needle biopsy is done to remove tissue samples from the affected area using guided ultrasound. The tissue samples are then sent to a lab for analysis to determine if these cells are abnormal or if they are cancerous or aggressive in nature.

DCIS is classified as a stage 0 cancer.

Treatment

DCIS is not an invasive breast cancer and, itself, is not a life-threatening condition. 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.

Treatment of DCIS is usually successful. Generally, it involves removing any abnormal tissue and preventing recurrences. 

Treatment may include:

• Lumpectomy: This is the surgical removal of the cancerous lump and a cancer-free margin of tissue. Since the chance of metastasis is so low, a 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: This usually follows a lumpectomy as a standard treatment for early-stage breast cancer.
• Hormonal therapy: These drugs reduce 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 is a perfect example of why it is important to have regular mammograms. It can be identified with imaging before it can be felt. As a very early-stage breast cancer, it usually doesn't need to be treated with chemotherapy. While even discussing the topic of breast cancer with your healthcare provider may be unsettling, know that DCIS usually responds well to treatment and has an excellent survival rate.