What is DCIS?

DCIS—ductal carcinoma in situ—is a very early, non-invasive breast cancer, classified as Stage 0.

DCIS is a ductal cancer that has not yet penetrated the lining of the duct. In other words, it is not invasive. In this in situ (“in place”) stage, the cancer has not spread into the blood stream and beyond. If it is diagnosed and treated correctly, the risk of dying from this cancer is essentially zero.

In the past, DCIS was rare—most breast cancers were found when the tumor had grown large enough to be felt by hand. By then it had time to spread outside the breast. But with the increased use of mammography in the past 25 years, DCIS has become relatively easy to detect. It appears on mammograms as microcalcifications: a speckling of tiny white dots that are clumps of dead cancer cells that became calcified inside the ducts.

About 60,000 cases of DCIS are diagnosed every year. DCIS has not yet been researched as extensively as the more common invasive breast cancer, and there is some disagreement among physicians as to how to treat it.


Mastectomy or Lumpectomy?

Until recently, it was firmly believed that the best way to treat DCIS was to perform a simple mastectomy. The feeling was that since the cancer has not yet spread (remember, DCIS is in situ!) all one had to do was remove the breast for essentially a 100% guarantee of cure. No chemotherapy, not radiation, no lymph node dissection.

When lumpectomy plus radiation became an acceptable choice for invasive breast cancer, surgeons learned that if they removed a small DCIS tumor with a wide margin around it, and treated the breast with radiation, they could achieve a much nicer cosmetic result.

But lumpectomy does carry a small chance of future local cancer recurrence. So the choice of treatment—mastectomy or lumpectomy—is up to the patient and her healthcare provider.


Radiation Therapy or Not?

The other area where there may be a difference of opinion is radiation therapy. This is where DCIS treatment differs from treatment of early invasive breast cancer. A Stage I or II (invasive) tumor treated with breast conserving surgery—lumpectomy—will always be treated with radiation too.

Some specialists believe that there is no need for radiating the breast if the DCIS tumor was small, and the margins were large and clear—in other words, if there is a fair degree of certainty that the tumor was indeed in situ.

The reason to avoid radiating a breast after a surgical excision of a DCIS tumor, is that if the cancer does recur in the future, the patient will no longer have the option of breast conserving surgery. Since radiation therapy can be used only once on the same area of the body, the next time, treatment will require a mastectomy, rather than a lumpectomy. This is another dilemma that requires discussion with your healthcare team.

Treatment of DCIS

To make the decisions easier, researchers devised a system for selecting the best treatment plan for each DCIS lesion. It is based on the size of the tumor, the grade of the tumor cells, and the width of the margins around the tumor. Here is how the procedure runs:

Before surgery, an accurate mammogram is obtained, to determine exactly the size and shape of the DCIS lesion.

During the operation, the surgeon removes the tumor with a large margin of normal tissue, striving for at least a half inch on all sides.

The radiologist takes an X-ray of the tissue removed and compares it with the original mammogram, to ensure that the entire tumor was removed.

Immediately after the X-ray, while the patient is still in the operating room, a pathologist makes numerous slices across the tumor and examines each slice in detail. Applying black ink to the outside of the tumor makes it easier to determine if the margins are “clear.”

If the tumor was small, the grade of the cells was low, and the margins were at least 10mm (less than half an inch) there may be no need for removing additional tissue, or for radiation therapy.

If the tumor was larger, the cells more aggressive, or the margins too narrow, then the DCIS tumor may be treated with a simple mastectomy, or lumpectomy with radiation.

Your Team

If you were diagnosed with DCIS, you may consider investing some time into finding a medical center with an experienced team—a surgeon, a pathologist and a mammographer who work well together in assessing in situ tumors. In this way you will be assured of the best chances for a successful treatment, with the least loss of breast tissue.