Ductal carcinoma in situ (DCIS)

Definition

In ductal carcinoma in situ (DCIS), abnormal cells multiply and form a growth within a milk duct of your breast. Although DCIS is an early form of breast cancer, it's noninvasive, meaning it hasn't spread out of the milk duct to invade other parts of the breast. Some experts consider DCIS to be a "preinvasive" condition. DCIS is the most common type of noninvasive breast cancer.

DCIS is usually found during mammogram screenings, but it can be difficult to detect. Because of increased screening with mammograms, the rate at which DCIS is diagnosed has increased dramatically in recent years. Fortunately, the condition isn't life-threatening, but it does require treatment. Unlike lobular carcinoma in situ (LCIS) — which really isn't a cancer at all but a marker for increased risk of developing invasive breast cancer — DCIS is more likely to develop into invasive breast cancer if left untreated.

Symptoms

DCIS usually has no outward signs or symptoms. However, some women may have a breast lump or nipple discharge associated with DCIS. Most often, though, DCIS is found on a screening mammogram, in which a radiologist identifies microcalcifications — tiny groups of calcium deposits — that indicate the presence of breast cancer. The microcalcifications appear on a mammogram as irregularly sized and shaped clusters of white spots.

Each of your breasts contains 15 to 20 lobes of glandular tissue, arranged like the petals of a daisy. The lobes are further divided into smaller lobules that produce milk during pregnancy and breast-feeding. Small ducts conduct the milk to a reservoir that lies just beneath your nipple. Supporting this network is a deeper layer of connective tissue called stroma. DCIS begins in the milk ducts of the breast.

Calcifications are small calcium deposits in the breast that show up as white spots on a mammogram. Large, round, well-defined calcifications (left column) are more likely to be noncancerous (benign). Tight clusters of tiny, irregularly shaped calcifications (right column) may indicate cancer.

Causes

Researchers don't know exactly what causes DCIS. Studies are ongoing exploring the interaction of genetics, environmental factors and hormonal exposures to better understand why some women develop breast cancer and others don't.

Risk factors

In general, the factors that put you at risk of developing DCIS are the same as risk factors for developing invasive breast cancer.

Things that increase your risk of DCIS include:

• Older age
• Personal history of benign breast disease, such as atypical hyperplasia
• Family history of breast cancer
• Never having been pregnant
• First pregnancy after age 30
• Genetic mutations, such as in the BRCA1 or BRCA2 genes

It's unclear whether postmenopausal hormone therapy puts you at greater risk of developing DCIS, but most reports haven't found an association between the two.

When to seek medical advice

Establish a schedule with your doctor for getting routine screening mammograms and clinical breast exams — and make sure you stick to it. Routine screening is the best way to detect the presence of DCIS. Also see your doctor if you discover changes in your breast, such as a breast lump, nipple discharge or any other unusual breast changes.

Tests and diagnosis

Mammography is the most beneficial tool in identifying DCIS. Because DCIS may be present in your breast even though you can't feel it, getting regular mammograms can help identify microscopic breast changes that might be associated with DCIS. The American Cancer Society recommends screening mammograms once a year for all women beginning at age 40.

If your radiologist identifies suspicious areas on your mammogram, such as shadows or bright white specks (microcalcifications), he or she will likely recommend a breast biopsy to evaluate that breast tissue.

You may undergo one of these biopsy procedures:

• Core needle biopsy. A radiologist or surgeon uses a hollow needle to remove tissue samples from the suspicious area. As many as 15 samples, each about the size of a grain of rice, may be taken then sent to a lab for analysis.
• Stereotactic biopsy. This type of biopsy also involves removing tissue samples with a hollow needle, but with the help of stereo images — mammogram images of the same area obtained from different angles — in finding (localizing) the area of concern.
• Surgical biopsy (wide local excision or lumpectomy). If results from a core needle biopsy or stereotactic biopsy show areas of increased cell growth (atypical hyperplasia) or DCIS, you'll likely need a surgical biopsy to remove a wider area of breast tissue for analysis. Surgical biopsy for DCIS can determine whether or not you also have invasive breast cancer.

During a core needle biopsy, your doctor inserts a special needle into the suspicious area of your breast and withdraws several small, solid cores of tissue to send for testing.

Treatments and drugs

Treatment of DCIS has a high likelihood of success, in most instances removing the tumor and preventing any recurrence, particularly a recurrence that spreads beyond the original site. The challenge is to avoid either overtreating or undertreating the condition.

Treatment options for DCIS include:

• Lumpectomy only
• Lumpectomy and radiation therapy
• Lumpectomy and the drug tamoxifen
• Simple mastectomy

Surgery
If you're diagnosed with DCIS, one of the first decisions you'll have to make is whether to treat the condition with breast-conserving surgery (lumpectomy) or breast-removing surgery (mastectomy).

• Lumpectomy. Lumpectomy removes only a portion of your breast. The procedure allows you to keep as much of your breast as possible, and depending on the amount of tissue removed, usually eliminates the need for breast reconstruction.

  Lumpectomy followed by radiation therapy is the most common treatment for DCIS. Research suggests that lumpectomy combined with radiation produces survival rates similar to those of mastectomy. Recurrence rates, however, are slightly higher for women treated with a lumpectomy than for women who undergo mastectomy.

  For older women with multiple medical conditions, lumpectomy plus tamoxifen therapy may be an option.

• Mastectomy. For treating DCIS, a simple mastectomy — removing the breast tissue, skin, areola and nipple, and possibly the underarm lymph nodes (sentinel node biopsy) — is one option. Breast reconstruction after mastectomy, if desired, can be performed in most cases. Because less extensive surgery, combined with radiation, may be equally effective, simple mastectomy is less common than it once was for treating DCIS.

Most women with DCIS are candidates for lumpectomy. However, mastectomy may be recommended if:

• You have a large area of DCIS. If the area is large compared with the size of your breast, a lumpectomy may not produce acceptable cosmetic results.
• There's more than one area of DCIS. It's difficult to remove multiple areas of DCIS with a lumpectomy. This is especially true if DCIS is found in different sections — or quadrants — of the breast.
• Tissue samples taken for biopsy show cancer cells at or near the edge (margin) of the tissue specimen. There may be more DCIS than originally thought, meaning that a lumpectomy might not be adequate to remove all areas of DCIS. If the area of DCIS is large, relative to the size of your breast, lumpectomy may produce unacceptable cosmetic results.
• You're not a candidate for radiation therapy. Radiation is usually given after a lumpectomy. You may not be a candidate if you're diagnosed in the first trimester of pregnancy, you've received prior radiation to your chest or you have a condition that makes you more sensitive to the side effects of radiation therapy.
• You prefer to have a mastectomy rather than a lumpectomy for any reason. For instance, you might not want a lumpectomy if you don't want to have radiation therapy. Or if you're a BRCA gene carrier, you might opt for preventive mastectomy to reduce your risk of breast cancer.

Surgery for DCIS typically doesn't involve removal of lymph nodes from under your arm because it's a noninvasive cancer. The chance of finding cancer in the lymph nodes is extremely small. If tissue obtained during surgery leads your doctor to think cancer may have spread outside the breast duct, he or she may then recommend a sentinel node biopsy or removal of some lymph nodes.

Radiation therapy
Radiation therapy after lumpectomy reduces the chance that DCIS will come back (recur) or that it will progress to invasive cancer. Radiation therapy uses high-energy X-rays to kill cancer cells or damage them to the point where they lose their ability to grow and divide. Because cancer cells multiply rapidly, they're more vulnerable to the effects of radiation than are normal cells. A type of radiation therapy called external beam radiation is most commonly used to treat DCIS.

Radiation might not be needed in selected cases, especially for older women with low-grade DCIS in a very small area of the breast.

Tamoxifen
Tamoxifen (Nolvadex) is a synthetic anti-estrogen hormone shown to be beneficial in the treatment of invasive breast cancer. It's also used as a cancer prevention (chemoprevention) agent for women at high risk of breast cancer. Tamoxifen is only effective against cancers that grow in response to hormones (hormone receptor positive cancers).

Tamoxifen isn't a treatment for DCIS in and of itself, but it can be considered as additional (adjuvant) therapy after surgery or radiation in an attempt to decrease your chance of developing a recurrence of DCIS or invasive breast cancer in either breast in the future. If you choose to have a mastectomy, there's less reason to use tamoxifen. With a mastectomy, the risk of invasive breast cancer or recurrent DCIS in the small amount of remaining breast tissue is very small. Any potential benefit from tamoxifen would apply only to the opposite breast. Discuss the pros and cons of tamoxifen with your doctor.

Factors that influence treatment
Several factors may influence treatment of DCIS. Researchers are attempting to identify which women are at high risk of recurrence and which are at low risk, based on the following factors:

• Pathologic margins. If cancer cells extend close to the edge of the tissue samples removed during a biopsy, there's a higher likelihood that some cancer cells have been left behind. In such a situation, wide excision — removing a larger area of breast tissue — or a mastectomy may be necessary.
• Tumor size. A small tumor has a better chance of being adequately removed with lumpectomy than does a larger tumor.
• Grade. In DCIS, grade refers to the appearance of the control centers (nuclei) of the cells. If, when examined under a microscope, the nuclei appear fairly similar to the nuclei of normal cells and very few cells are dividing, the tumor is low grade. If the nuclei are markedly different from the nuclei of normal cells, or if they're dividing rapidly, or both, the tumor is high grade. High-grade tumors have a higher rate of developing into invasive breast cancer than do low-grade tumors.
• Cell structure. Two major subtypes of DCIS are distinguished by the structure of their cells. One type is characterized by large, atypical cells with a central area of dead or degenerating cells (comedo necrosis). The other type is characterized by the lack of these qualities. The presence of comedo necrosis generally signifies a more aggressive lesion. Tumors with comedo necrosis have a higher rate of recurrence than do DCIS tumors without comedo necrosis.
• Age. If DCIS is diagnosed when you're younger than age 40, you may be at higher risk of recurrence than a woman age 40 or older.

Coping and support

Any cancer diagnosis can be overwhelming and scary, even if it's a noninvasive, treatable form of cancer, such as DCIS. To better cope with your diagnosis, it may be helpful to:

• Educate yourself. The more you know about DCIS and your treatment options, the better prepared you'll be to make the best choices. Asking questions of your doctor or other members of your medical team is a good place to start. There are also excellent books on breast cancer and many reputable resources on the Internet. Be sure to look for the most current information because breast cancer treatments change rapidly. It may also help to talk with women who have been through a similar experience.
• Get support when needed. Don't be afraid to ask for help or to turn to a trusted friend when you need to share your feelings and concerns. Talk with a counselor or medical social worker if you need a more objective audience. Join a support group — in real life or online — of women going through a situation similar to yours.

It may take time to sort through your emotions, but you can still be in charge of your life and participate actively in decisions about your treatment.