DCIS (Ductal Carcinoma In Situ)

What DCIS means

The breast contains lobules that make milk and ducts that carry it to the nipple. In DCIS, cells lining a duct have become cancerous and multiplied, but they remain inside the duct wall (in situ means "in its original place"). Because they have not broken through the duct wall, they cannot reach blood vessels or lymph channels to spread.

DCIS accounts for about 1 in 5 breast cancers diagnosed through screening. Not all DCIS would progress to invasive cancer within a person's lifetime, and researchers are working on ways to identify low-risk DCIS that may not need full treatment.

Symptoms

Most DCIS causes no symptoms. Occasionally it causes:

• a breast lump
• bloody nipple discharge from one duct
• Paget's disease of the nipple: a red, scaly, itchy rash on the nipple

Diagnosis

1. Mammogram: DCIS often appears as clusters of tiny calcium deposits (microcalcifications). Further magnified views are taken.
2. Core needle biopsy: usually a stereotactic (mammogram-guided) biopsy removes small tissue samples.
3. Pathology: the report describes: - Grade: low (1), intermediate (2) or high (3). High-grade DCIS is more likely to recur or become invasive. - Hormone receptor status: whether the cells have estrogen receptors (ER) and progesterone receptors. - Comedo necrosis: dead cells in the center of ducts, associated with higher grade.
4. MRI is sometimes used to assess extent.

Because a biopsy samples only part of the area, invasive ductal carcinoma is occasionally found when the whole area is removed.

Treatment

The goal is to remove the DCIS and lower the chance of it coming back or developing into invasive cancer.

Breast-conserving surgery (lumpectomy)

The surgeon removes the area of DCIS with a rim of normal tissue (a clear margin, usually at least 2 mm). Lymph nodes are not usually removed for DCIS treated by lumpectomy.

Radiation therapy

Radiation after lumpectomy roughly halves the risk of recurrence in the same breast. Some people with small, low-grade DCIS and wide margins, especially older adults, may choose to skip radiation after discussion of the trade-offs.

Mastectomy

Removing the whole breast may be recommended for widespread DCIS, DCIS in several areas, or when clear margins cannot be achieved. Some choose mastectomy for personal reasons or because of a high genetic risk. A sentinel lymph node biopsy is often done with mastectomy in case invasive cancer is found. Breast reconstruction is an option.

Hormone therapy

For ER-positive DCIS, tamoxifen (or an aromatase inhibitor after menopause) for 5 years can reduce the risk of recurrence and new breast cancers. It is optional and depends on weighing benefits against side effects.

Active monitoring

Clinical trials are studying whether some low-risk DCIS can be safely watched with regular imaging instead of surgery. This is not standard care outside of trials.

Recurrence

About 10% to 15% of women treated with lumpectomy and radiation have a recurrence within 10 to 15 years; about half of recurrences are invasive cancer. Risk is higher with high-grade DCIS, close margins, younger age and larger size. Recurrence after mastectomy is uncommon.

Follow-up

• clinical breast exams every 6 to 12 months for 5 years, then yearly
• yearly mammograms of the treated and other breast
• genetic counseling for people with a strong family history or diagnosis at a young age; see BRCA mutation

Frequently asked questions

Is DCIS really cancer?

DCIS is considered a non-invasive, stage 0 cancer. The cells are cancerous but confined to the milk ducts, so they cannot spread while they remain there. It is treated to prevent it from becoming invasive breast cancer.

Does DCIS always turn into invasive cancer?

No. Some DCIS, particularly low-grade DCIS, may never become invasive in a person's lifetime. However, there is currently no reliable way to tell which will progress, so treatment is generally recommended. High-grade DCIS has a higher risk of progression.

Do I need radiation after lumpectomy for DCIS?

Radiation reduces the risk of recurrence in the same breast by about half, but does not change overall survival. For small, low-grade DCIS with wide margins, some people choose to skip it. Your care team can help you weigh the benefits and side effects.

What is the survival rate for DCIS?

The outlook is excellent. Studies show breast cancer-specific survival of about 98% or higher at 10 to 20 years after diagnosis. The main concern is recurrence, which is why follow-up mammograms and exams are important.

Does DCIS need chemotherapy?

No. Because DCIS has not invaded beyond the ducts, chemotherapy is not used. Treatment is surgery, often with radiation, and sometimes hormone therapy for hormone receptor-positive DCIS.