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A diagnosis of breast cancer in situ is made by the pathologist who examines a biopsy specimen under the microscope. The diagnosis of breast cancer in situ implies that the biopsy shows a non-invasive or pre-malignant condition that is not truly an invasive cancer. Breast cancer in situ is classified as either ductal carcinoma in situ (DCIS) arising from ductal epithelium or lobular cancer in situ (LCIS) arising from the epithelium of the lobules. With the increasing use of screening mammography, non-invasive cancers (DCIS and LCIS) are more frequently diagnosed and now constitute 15-20% of all breast cancer. Ductal carcinoma in situ is thought to be a direct precursor of invasive breast cancer, is highly curable, and removal prevents invasive breast cancer. Lobular carcinoma in situ is thought to be an indicator for an increased risk of developing invasive breast cancer but may not be the direct precursor abnormality. The role of early treatment is less clear for patients with lobular carcinoma in situ.
Ductal Carcinoma in Situ
Ductal carcinoma in situ (DCIS) is the earliest possible clinical diagnosis of breast cancer and is frequently diagnosed with screening mammography which has detected small areas of calcification in the breast. Patients rarely suspect that they have breast cancer with this stage cancer. It is estimated that the average time to develop invasive breast cancer from DCIS is 5-8 years.
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 to your situation. In addition to this treatment overview, the Clinical News web site feature presents the results of the actual clinical trials that determine the standard treatments of DCIS and new treatment strategies as they have been discovered and applied by cancer physicians around the world.
All new treatments are developed in clinical trials. Participation in a clinical trial may offer access to better treatments and advance the existing knowledge about treatment of this cancer. Remember that this web site information 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.
Ductal carcinoma in situ can be thought of as a pre-cancerous or early stage growth of abnormal cells in the ducts of the breast. Historically, ductal carcinoma in situ (DCIS) was an extremely uncommon finding in women, and little attention was given to defining its optimal treatment. This is because ductal carcinoma in situ can be cured almost 100% of the time with a surgical mastectomy. With the increased use of screening mammography, women are more likely to have cancer diagnosed at an earlier stage, and therefore, the number of women diagnosed with ductal carcinoma in situ is increasing. If DCIS is untreated, approximately 30% of patients will develop invasive breast cancer an average of 10 years from the initial diagnosis.
The Role of Surgery
Because of advances in cancer detection and therapy, the treatment options for women with DCIS are many. In the past, surgical removal of the affected breast, called mastectomy, was recommended. 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 recently began using breast-conserving surgery to treat DCIS successfully, without removal of the 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 because ductal carcinoma in situ is a pre-cancerous or early stage lesion. It is extremely unlikely for cancer to have spread to the axillary lymph nodes and most studies indicate that approximately 4% of patients will have axillary lymph node involvement with their cancer. Determining which patients should undergo axillary lymph node dissection is difficult; however, most doctors recommend that patients with either extensive DCIS or those with high grade comedotype cancers should consider axillary lymph node dissection.
Following breast conservation surgery, recurrence rates appear to be related to the margin 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 lesions, multiple areas of DCIS or in women who cannot undergo radiation therapy.
For some patients with small cancers and wide margins, surgery alone is probably curative with an extremely low rate of recurrence. However, as a generality, most patients undergoing lumpectomy will probably be advised to receive radiation therapy with or without tamoxifen for maximum prevention of recurrences.
Role of Radiation Therapy
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 surgical margins were randomly assigned to receive breast radiation or no further therapy after a lumpectomy. At 8 years, the recurrence of invasive cancer was 3.9% for patients treated with radiation and 13.4% for patients not treated with radiation.
Role of Hormonal 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 and is commonly used in many countries. Chemotherapy also causes ovarian failure and can prevent estrogen release in many patients. Another approach is to utilize drugs that can accomplish a similar effect without removing the ovaries. The most common drug utilized in the hormonal treatment of breast cancer is tamoxifen. Tamoxifen works by blocking estrogen receptors and preventing the estrogen stimulated growth of the breast cancer cells. Tamoxifen is often referred to as an anti-estrogen.
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 ductal carcinoma in situ (DCIS). 1804 women with DCIS 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 to 13.4% for patients receiving placebo. The incidence of invasive breast cancer in the tamoxifen group was 4.1% at 5 years, 2.1% in the same breast and 1.8% in the opposite breast and 0.2% at regional or distant sites. It was concluded that surgery, radiation therapy and tamoxifen was more effective prevention of invasive breast cancer in patients with DCIS than surgery and radiotherapy. However, there was no survival differences between the 2 groups. The risks and benefits of tamoxifen treatment should be discussed with your physician.
Strategies to Improve Outcomes
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 patients and doctors continuing to participate in appropriate studies. Areas of active exploration to improve the treatment of DCIS include the following: