Ductal carcinoma in situ (DCIS)

Ductal carcinoma in situ, or DCIS, occurs when abnormal cells are found in the lining of the milk ducts, the tubes that carry milk to the nipple. “In situ” means the cancer is contained inside the ducts. It hasn’t broken through the duct walls and moved into nearby healthy breast tissue. As a result, DCIS can’t spread to other areas of the body.

You may hear other terms used to describe DCIS, such as:

• Intraductal carcinoma
• Noninvasive or pre-invasive breast cancer
• Stage 0 breast cancer

DCIS accounts for about 1 in 5 breast cancers diagnosed each year. It has the potential to develop into invasive breast cancer, also called invasive ductal carcinoma, which can spread to other parts of the breast.

DCIS is different than lobular carcinoma in situ (LCIS). LCIS happens when abnormal cells grow inside the lobules, or milk-making glands. LCIS is not cancer. However, people with LCIS are at higher-than-average risk of developing breast cancer in the future. If cancer develops, the cancer can be lobular or ductal, and it can happen in either breast.

DCIS is much more common than LCIS. LCIS is found in only about 2 to 2.5% of breast biopsies.

DCIS and the risk of invasive breast cancer

If left untreated, anywhere from 25 to 60% of DCIS cases will develop into invasive breast cancer (invasive ductal carcinoma).

Even with treatment, about 5 to 10% of people diagnosed with DCIS will develop invasive breast cancer later in life. In most cases, the cancer is related to the original DCIS. However, it’s also possible to develop an unrelated breast cancer.

Some groups appear to be at higher risk of developing invasive breast cancer after DCIS. For example:

• Black and Asian women have a higher risk than White women for developing breast cancer with aggressive features in the years after a DCIS diagnosis.
• People who are diagnosed with both DCIS and LCIS have a higher risk of later developing breast cancer in the opposite breast, versus people with DCIS alone. The risk of a new cancer in the same breast appears to be similar for both groups.

There’s no way to tell for certain which cases of DCIS will progress into breast cancer and which won’t. That is why doctors recommend surgery to remove DCIS, possibly with other treatments such as radiation therapy. If the DCIS is hormone receptor-positive, hormonal therapy may be recommended to reduce the risk of recurrence.

There are genomic tests that can predict the risk of recurrence after DCIS, and whether radiation therapy is likely to benefit you. These tests look at the activity of certain genes in a tumor sample to learn more about the cancer’s behavior. Examples include the Oncotype DX Breast DCIS Score test.

You can learn more about these tests below.

Diagnosing DCIS

DCIS is diagnosed based on imaging and other tests:

• Mammogram: A test that uses low-dose x-rays to create images of the breast
• Breast ultrasound: An imaging test that uses high-frequency sound waves to detect lumps, cysts, and other changes in the breast
• Breast MRI: An imaging test that creates detailed, 3D pictures of breast tissue using a magnetic field and radio waves
• Biopsy: A procedure that removes a sample of the abnormal tissue, or the entire tumor, so it can be examined under a microscope

After a biopsy, a pathologist — a doctor who specializes in diagnosing disease — will examine the DCIS to identify important characteristics that can help determine treatment options. In the days after biopsy, you’ll receive a pathology report that provides information about:

• The size of the DCIS
• Whether the DCIS is in one or multiple locations in the breast
• The grade of the DCIS. This can be:
  • Low grade / nuclear grade 1: The cells divide and grow slowly.
  • Intermediate grade / nuclear grade 2: The cells divide and grow at a moderate rate.
  • High grade / nuclear grade 3: The cells divide and grow quickly.
  • Intermediate- and high-grade DCIS is more likely to come back after surgery.
• The appearance and growth pattern of the cells. If the DCIS is low or moderate grade, you may see terms such as papillary, cribriform, or solid to describe how the cells appear under a microscope. High-grade DCIS is sometimes called comedo. This means that some of the cells are dead (necrotic) because they are growing and dividing so quickly. Your doctor can help you understand how this information affects the chance of DCIS coming back after treatment.
• Margin status: Whether a cancer-free margin of tissue around the DCIS was successfully removed

Immunohistochemistry testing is also done to confirm whether the cancer has receptors for the hormones estrogen and progesterone. If the cancer has hormone receptors, it means that hormones are helping the DCIS cells to grow and multiply. Hormone receptor-positive DCIS can be treated with hormonal therapy that either blocks estrogen’s activity or lowers overall estrogen levels.

In other types of breast cancer, immunohistochemistry testing also looks for HER2 receptors, which are proteins that signal cancer cells to grow. DCIS isn’t tested for HER2 receptors because treatments that target HER2 are only recommended for invasive breast cancer, not DCIS.

Learn more in Understanding your pathology report.

Testing for inherited genetic mutations

Certain inherited genetic mutations — or abnormal changes in genes — increase breast cancer risk. Inherited gene mutations are passed down by a parent.

The American Society of Clinical Oncology recommends that all newly diagnosed patients under age 65 be tested for BRCA1 and BRCA2 gene mutations. These are the two genetic mutations most strongly associated with increased breast cancer risk.

In some cases, tests for other high-risk inherited gene mutations are also recommended.

Some factors that suggest DCIS may be linked to an inherited mutation include:

• You’re under age 50.
• You’ve had DCIS or another breast cancer before.
• Your family tree includes one or more relatives who had breast cancer and/or ovarian cancer.
• You have a blood relative who has already tested positive for an inherited BRCA1 or BRCA2 gene mutation or another breast cancer-related mutation.

Talk with your doctor about genetic counseling. A genetic counselor can explain the process of genetic testing. The results can help you:

• Make more informed treatment decisions with your doctor.
• Assess your risk of developing breast cancer in the future.
• Talk with family members about whether they may be at increased risk and may want to consider genetic testing.

Visit Genetic testing for inherited mutations to learn more.

Testing for risk of recurrence

In early-stage breast cancer such as DCIS, genomic tests look at the activity of certain genes in the tumor tissue to learn more about the risk of cancer coming back (recurrence). Testing can be done on tissue removed during a biopsy or during a lumpectomy or mastectomy surgery. This information can help with selecting treatments to lower that risk.

Doctors often use the Oncotype DX Breast DCIS Score test to look at tumor tissue gene activity. This test can confirm:

• The 10-year risk of the DCIS coming back in the same breast
• The 10-year risk of the DCIS returning as invasive breast cancer
• Whether you’re likely to benefit from radiation therapy

Learn more about Oncotype DX.

Talk with your healthcare team about your testing options.

Treating DCIS

The goals of DCIS treatment are to remove all the DCIS and lower the risk of the cancer coming back, whether as DCIS or invasive breast cancer. Your recurrence risk can be higher or lower depending on:

• The grade and growth patterns of the DCIS
• How large the tumor is
• The results of genomic tests, such as Oncotype DX

Your care team will work with you to help you understand the features of the DCIS and how they impact treatment planning. Below, you can read about treatment options for DCIS.

Surgery

Your treatment plan will always include surgery. Options include:

Lumpectomy

Lumpectomy, also called breast-conserving surgery, removes the DCIS and a margin (or rim) of healthy tissue around it.

Mastectomy

Mastectomy, or surgery to remove all of the breast tissue, may be recommended if:

• The area containing DCIS is large relative to the size of the breast.
• There are multiple areas of DCIS in different parts of the breast.
• Cancer was found in the surrounding rim of tissue removed during lumpectomy. This is called a positive margin.
• You’ve tested positive for a BRCA1, BRCA2, or other inherited genetic mutation that increases lifetime breast cancer risk. In this case, some people may decide to have both breasts removed (called prophylactic, or preventive, mastectomy).
• You’re not a candidate for radiation therapy, which is often recommended after lumpectomy. This might be due to pregnancy, past chest radiation, or other health conditions.

Lymph node surgery

Lymph node surgery removes one or more underarm lymph nodes so doctors can check for any signs of cancer spread.

Breast reconstruction

If you and your care team decide that mastectomy is the best option for you, let your surgeon know if you want to have breast reconstruction. Not everyone chooses to have their breasts rebuilt after mastectomy. Many people decide to go flat instead.

Your surgeon can refer you to a plastic surgeon specializing in different reconstructive techniques to help you decide.

Additional DCIS treatments

Additional treatments may include:

Radiation therapy

Radiation therapy directs high-energy x-rays to the breast area. Your doctor may recommend whole breast radiation, which delivers radiation to the entire breast, or partial breast radiation, which focuses on the area where the DCIS was found.

In most cases, radiation therapy isn’t needed if you have a mastectomy. It might not be needed if you had lumpectomy and:

• Had a slow-growing, small DCIS
• The DCIS has a low risk of recurrence based on features and test results
• The cancer was completely removed during surgery

Hormonal therapy

Hormonal therapy may be recommended if the DCIS tests positive for hormone receptors. These treatments block or lower estrogen so it can no longer help the cancer grow. Options include tamoxifen or an aromatase inhibitor.

Chemotherapy is not usually recommended for DCIS.

If invasive breast cancer is found after biopsy or surgery

It’s important to know that in 15 to 20% of DCIS cases, invasive breast cancer is found after biopsy, lumpectomy, or mastectomy.

Invasive breast cancer includes invasive ductal carcinoma, invasive lobular carcinoma, and other breast cancers. If invasive breast cancer is found, your treatment plan will change based on the breast cancer’s type and the specific features of the cancer.

Learn more on the Types and subtypes of breast cancer page.

Follow-up care for DCIS

After treatment for DCIS, you and your care team will decide on a follow-up plan. Your plan may include:

• A doctor visit and clinical breast exam every 6 to 12 months
• A mammogram 6 to 12 months after lumpectomy or lumpectomy plus radiation, and then annually

Your care team will let you know if they recommend additional imaging for breast screening, such as ultrasound or breast MRI.

Read When to have follow-up visits for more information.