Ductal Carcinoma In Situ (DCIS)

What DCIS is

The breast contains milk ducts lined by cells. In DCIS, some of these cells become cancerous but remain inside the duct, held back by its wall (the basement membrane). Because they have not invaded, they cannot reach lymph vessels or blood vessels, so DCIS by itself does not spread to other parts of the body.

DCIS is considered a non-obligate precursor of invasive breast cancer. Some DCIS lesions would progress to invasive ductal carcinoma if left untreated, while others might never cause harm. Research is under way to tell which is which.

Around 1 in 5 breast cancers diagnosed in the US is DCIS, largely because of mammography screening.

Symptoms

Most DCIS has no symptoms. Occasionally it causes:

• a breast lump
• bloody discharge from one nipple
• Paget disease of the nipple, with red, scaly, itchy skin on the nipple

Diagnosis

1. Screening mammogram: shows tiny clusters of calcium (microcalcifications).
2. Diagnostic mammogram with magnified views.
3. Core needle biopsy: usually stereotactic (mammogram-guided). The pathologist confirms DCIS.
4. MRI in selected cases to check extent.

The pathology report describes features that guide treatment:

• Grade: low (1), intermediate (2) or high (3). High grade is more likely to recur or progress.
• Necrosis: dead cells in the ducts, linked to higher risk.
• Hormone receptor status: estrogen receptor (ER) positive DCIS can be treated with hormone therapy.
• Size and margins after surgery.

Benign conditions such as fibrocystic breast changes can also cause calcifications, which is why a biopsy is needed. A small percentage of DCIS found on biopsy is upgraded to invasive cancer after surgery removes the full area.

Treatment options

Surgery

• Lumpectomy (breast-conserving surgery): removes the DCIS with a margin of normal tissue. Most women are suitable. A clear margin of at least 2 mm is the standard when radiation is given.
• Mastectomy: removal of the breast, recommended for large or widespread DCIS or when clear margins cannot be achieved, or chosen by personal preference. Reconstruction can be done at the same time.
• Lymph node surgery is not routinely needed for DCIS treated with lumpectomy. A sentinel node biopsy may be done with mastectomy, because it cannot be done afterward if invasion is found.

Radiation

Radiation after lumpectomy reduces the risk of recurrence in the same breast by about half. About half of recurrences are invasive. Some women with small, low-risk DCIS may choose to skip radiation after discussing risks, and genomic tests can help with this decision.

Hormone therapy

For ER-positive DCIS, tamoxifen or an aromatase inhibitor (after menopause) for 5 years lowers the risk of recurrence and of new cancer in either breast. It does not improve survival, so the choice depends on side effects and personal preference.

Active monitoring

Clinical trials are testing whether some women with low-risk DCIS can be safely monitored instead of having surgery. Outside a trial, surgery remains the standard approach.

Recurrence and outlook

Survival is excellent with all approaches. Large studies show that the risk of dying from breast cancer after DCIS is low and similar to that of the general population in many groups. Younger age at diagnosis and high-grade disease raise risk somewhat.

Follow-up and living after DCIS

• clinical breast exams every 6 to 12 months for 5 years, then yearly
• yearly mammograms of both breasts
• report any new lump, nipple change or skin change promptly
• maintain a healthy weight, be physically active and limit alcohol, which lowers breast cancer risk
• genetic counseling if you were diagnosed young or have a strong family history of breast or ovarian cancer

Frequently asked questions

Is DCIS considered cancer?

DCIS is a non-invasive cancer, also called stage 0 breast cancer. The cells are cancerous but stay inside the milk ducts and cannot spread elsewhere unless they become invasive. It is treated to remove it and lower the chance of invasive breast cancer developing.

Does DCIS always turn into invasive cancer?

No. Some DCIS would never progress, but some would become invasive if untreated. Doctors cannot yet reliably tell which lesions will progress, which is why surgery is usually recommended. High-grade DCIS has a higher chance of progression.

What is the treatment for DCIS?

The main options are lumpectomy with radiation, lumpectomy alone in selected low-risk cases, or mastectomy. Women with estrogen receptor positive DCIS may also take tamoxifen or an aromatase inhibitor for 5 years to reduce the risk of recurrence.

Do I need chemotherapy for DCIS?

No. Chemotherapy is not used for DCIS, because the cells have not invaded and cannot spread through the body. Treatment focuses on surgery, sometimes radiation, and sometimes hormone therapy.

What is the survival rate for DCIS?

Survival is excellent. In large studies, the risk of dying from breast cancer within 20 years of a DCIS diagnosis is around 3%, close to that of women in the general population. Most women with DCIS live normal lifespans.