Carcinoma in Situ

There are two types of breast carcinoma in situ: ductal carcinoma in situ (DCIS) and lobular carcinoma in situ (LCIS). DCIS is a very early stage of breast cancer in which the abnormal cells are confined to the lining of breast ducts. If not treated, an estimated 40% of DCIS cases will progress to invasive cancer. LCIS, in contrast, is not believed to be a direct cancer precursor, but does indicate that a woman is at increased risk of developing breast cancer. The role of early treatment is less clear for patients with LCIS. For more information, go to Lobular Carcinoma In Situ.

Ductal carcinoma in situ (DCIS) is the earliest possible clinical diagnosis of breast cancer and is frequently diagnosed with screening mammography that has detected small areas of calcification in the breast. Patients rarely suspect that they have breast cancer with this stage cancer.

A variety of factors ultimately influence a patient's decision to receive treatment of cancer. The purpose of receiving cancer treatment may be to improve symptoms through local control of the cancer, increase a patient's chance of cure, or prolong a patient's survival. The potential benefits of receiving cancer treatment must be carefully balanced with the potential risks of receiving cancer treatment.

The following is a general overview of the treatment of DCIS. Circumstances unique to your situation and prognostic factors of your cancer may ultimately influence how these general treatment principles are applied. The information on this Web site is intended to help educate you about your treatment options and to facilitate a mutual or shared decision-making process with your treating cancer physician.

Most new treatments are developed in clinical trials. Clinical trials are studies that evaluate the effectiveness of new drugs or treatment strategies. The development of more effective cancer treatments requires that new and innovative therapies be evaluated with cancer patients. Participation in a clinical trial may offer access to better treatments and advance the existing knowledge about treatment of this cancer. Clinical trials are available for most stages of cancer. Patients who are interested in participating in a clinical trial should discuss the risks and benefits of clinical trials with their physician. To ensure that you are receiving the optimal treatment of your cancer, it is important to stay informed and follow the cancer news in order to learn about new treatments and the results of clinical trials.

In the past, surgical removal of the affected breast, called mastectomy, was recommended for the treatment of DCIS. This treatment has resulted in cure rates of 98 to 99%. Rare cancer recurrences occur in the axilla, the opposite breast, or at distant sites. Because of this success, doctors began using breast-conserving surgery to treat DCIS successfully, without removal of the entire breast. This type of surgery may involve a partial mastectomy (removal of the cancer, some of the healthy breast tissue, and sometimes the area lymph nodes), or a lumpectomy (removal of the cancer and the tissue around the cancer).

Axillary lymph node dissection is not routinely performed for DCIS because it’s uncommon for DCIS to involve the lymph nodes. In certain situations, however, sentinel lymph node biopsy may be considered.

Total Mastectomy: Total mastectomy involves complete removal of the breast and is associated with a cure rate of nearly 98-99%. Women treated with total mastectomy require no additional treatment to the affected breast.

Breast-Conserving Surgery: Although no randomized trials have been performed, breast-conserving surgery has been used successfully to treat DCIS in the last 30 years. A current goal of treatment for women with DCIS is breast conservation with an optimal cosmetic effect and a minimum risk of subsequent invasive or in situ cancer recurrence. Current clinical studies suggest that women treated in this manner may have a slightly higher risk of cancer recurrence than women treated with mastectomy; however, the risk of dying of complications of breast cancer is probably only 2-3% at 10 years following diagnosis, but may be greater at 15-20 years.

Following breast-conserving surgery, recurrence rates appear to be related to the margin (amount of normal tissue removed surrounding the cancer) between the surgically removed DCIS and normal tissue. There is a consensus that adequate surgery includes a 10-millimeter or greater margin between DCIS and normal tissue. Breast conservation surgery is advised for the majority of women with small (2-3 centimeters) cancers with margins of 10 millimeters or greater or cancer of intermediate nuclear grade. Mastectomy is currently reserved for the minority if women with large cancer, multiple areas of DCIS or in women who cannot undergo radiation therapy.

For some patients with small cancers and wide surgical margins, surgery alone is probably curative, with an extremely low rate of recurrence. However, in general, most patients undergoing breast-conserving surgery will probably be advised to receive radiation therapy with or without hormonal treatment for maximum prevention of recurrences.

Patients treated with mastectomy do not need additional treatment with radiation therapy. It is clear that radiation therapy following lumpectomy decreases total recurrences. In one clinical study, 818 women with DCIS and negative (no cancer detected) surgical margins were randomly assigned to receive breast radiation or no further therapy after a lumpectomy. Eight years following treatment, the recurrence of invasive cancer was 3.9% for patients treated with radiation and 13.4% for patients not treated with radiation.[1] To learn more, go to Radiation Therapy.

Estrogen is a female hormone produced mainly by the ovaries. Many organs in the body are composed of cells that respond to or are regulated by exposure to estrogen. Cells in the breast, uterus and other female organs have estrogen receptors and when exposed to estrogen, are stimulated to grow. When cells that have estrogen receptors become cancerous, the growth of these cancer cells can be increased by exposure to estrogen. The basis of hormonal therapy as a treatment for breast cancer is to block or prevent the cancer cells from being exposed to estrogen.

Removal of the source of estrogen production, the ovaries, is one effective approach to eliminating estrogen production in premenopausal women, and is commonly used in many countries. Another approach is to utilize drugs such as tamoxifen. Tamoxifen works by blocking estrogen receptors and preventing the estrogen-stimulated growth of the breast cancer cells.

A clinical study has been performed to determine whether lumpectomy, radiation therapy, and tamoxifen are of greater benefit than lumpectomy and radiation therapy without tamoxifen therapy for treatment of DCIS. The study involved 1,804 women with DCIS who were randomly assigned to lumpectomy, radiation therapy and placebo or lumpectomy, radiation and tamoxifen for 5 years. The average follow-up was 74 months. Women treated with tamoxifen had an incidence of invasive and non-invasive cancer recurrences of 8.2%, compared with 13.4% for patients receiving placebo.[2] 

The progress that has been made in the treatment of DCIS has resulted from doctor and patient participation in clinical studies. Future progress in the treatment of DCIS will result from continued participation in appropriate studies. Areas of active exploration to improve the treatment of DCIS include the following:

Attempts to identify patients who do not require radiation therapy: There have been attempts to identify patients who can be cured with breast-conserving surgery alone by examination of the characteristics of the DCIS. Improvements in this area could spare many patients the need for radiation therapy.

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