Ductal Carcinoma In Situ (DCIS)

DCIS is the earliest form of breast cancer, in which the cancer cells are contained within the walls of the milk duct. It is also known as intraductal carcinoma in situ (or cancer located within the milk ducts). Because the cancer cells have not broken through the wall of the duct, the cancer cells have no access to the blood stream or the lymph nodes, and have no ability to spread to other parts of the body. As a result, DCIS is completely curable. Women do not die of DCIS.

However, it is important to treat DCIS aggressively, because DCIS lesions can develop the ability to invade through the wall of the mild duct and spread to other parts of the body. Treatment for DCIS is designed to prevent that from happening.

There is some controversy as to whether DCIS is truly cancer, as it is becoming increasingly clear that some DCIS will never develop into invasive breast cancers

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Unfortunately, we do not have the ability at this time to know which DCIS have the potential to invade and spread, and which ones will never cause any problems. This is an area of active investigation in the laboratories at NYU.

How is DCIS diagnosed?

In the past, DCIS was rarely diagnosed because we did not have any tests for screening for breast cancer other than physical examination. By the time a lump was detected, the cancer cells had most often invaded through the wall of the duct to form an invasive breast cancer. Now that we have good quality screening mammograms, DCIS accounts for as much as 30 percent of all breast cancers diagnosed. The most common finding leading to the diagnosis of DCIS is clusters of tiny calcium deposits seen in the breast on a mammogram. Once such abnormalities are identified, a biopsy is performed, preferably with a needle, if possible.

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Pathology of DCIS

DCIS is actually a spectrum of diseases with a variety of descriptive characteristics. DCIS is typically described by its architecture, nuclear grade, the distribution within the breast, and whether or not necrosis (dead tumor cell debris inside the center of the milk duct) is present.

Architectural Types:  
Papillary (Walls of the duct have larger projections of tumor cells [like polyps in the colon].) Less Aggressive
Micropapillary (Walls of the duct have tiny projections of tumor cells.)
Cribriform (Duct is filled with bridging and interweaving structures composed of cancer cells.)
Solid (Ducts are packed solid with cancer cells.)
Comedo (The center of the duct contains the debris of dead cells.) More Aggressive

Nuclear Grade: Nuclear grade is a measure of how abnormal the nucleus (structure in the center of the cell that contains the genetic material of the cell) appears under the microscope. Nuclear grade is measured on a scale of 1 to 3, with 1 being the most normal appearing and 3 being the most abnormal. The high grade (grade 3) DCIS lesions appear to be the most aggressive.

Distribution: DCIS is usually confined to one area (or focus) within a single milk duct and so is called unifocal. If it is present in several separate areas within the same duct (separate lesions, but close together) it is called multifocal. When DCIS is present in widely separate areas, likely representing different milk ducts, it is called multicentric.

Necrosis (or comedo necrosis): Necrosis refers to the presence of dead tumor cell debris inside the center of the milk duct. It often looks like a pasty or cheesy material. Necrosis happens when the cancer cells grow so vigorously within the milk duct that they outgrow the blood supply. The cells then starve to death and decay, leaving debris behind. The presence of necrosis suggests an aggressive form of DCIS.

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Treatment of DCIS

The most important thing to remember about DCIS is that it is not a fatal disease. You are unlikely to die of breast cancer regardless of what form of treatment you receive. The goal of treatment for DCIS is to prevent you from developing an invasive breast cancer. DCIS, like all breast cancers, can be treated with either mastectomy (the removal of the entire breast, with or without reconstruction) or with breast-conserving surgery. Mastectomy removes almost all of the breast tissue and decreases the risk of developing an invasive breast cancer to less than 1 percent. However, many feel that mastectomy is too aggressive a treatment for this condition. The alternative is breast-conserving surgery, often called a lumpectomy, partial or segmental mastectomy, or a quadrantectomy. This type of surgery involves removing the DCIS with a rim of normal tissue around it (referred to as the surgical margin). Margins should be negative (no tumor cells at the edge of the removed tissue) after breast conserving surgery. Because DCIS usually cannot be felt or seen with the naked eye and is often involving a larger area than can be seen on mammogram, it sometimes takes several tries to achieve negative margins. In some cases, such as when the DCIS is very large or multicentric, it may not be possible to achieve negative margins, and breast-conserving surgery should not be performed. Women in these situations should undergo mastectomy.

There is a real risk of developing a recurrence of the cancer in the area of the surgery following breast-conserving surgery (up to one in four women will develop a local recurrence in the breast within five years after breast-conserving surgery alone). This risk is cut in half when the surgery is followed with radiation treatments. For this reason, either mastectomy (with reconstruction, if desired), or breast-conserving surgery followed by six weeks of radiation treatments (the combination of breast-conserving surgery with radiation is often referred to as breast-conserving therapy) is considered the standard treatment for DCIS. Some people question the necessity of radiation treatments in all patients. It is possible that there are some women for whom radiation can be avoided, but there is currently no proof of the safety of this approach. The need for radiation in your individual case should be discussed with your physicians.

Recent studies have shown that in up to 50 percent of cases, both local recurrences and new breast cancers in the opposite breast can be prevented by taking tamoxifen, an anti-estrogen drug, for five years following breast-conserving therapy for breast cancer. There are some risks associated with tamoxifen therapy, and you should discuss these with your doctors.

Links

American Cancer Society on Breast Cancer

National Cancer Institute on Breast Cancer