Ductal carcinoma in situ is a type of breast cancer that occurs in the connecting tubes, or ducts, of the breast. This cancer, which is confined to the duct, is almost always curable. Even if this cancer recurs (returns) after therapy, it can often be treated successfully. However, there are rare occasions when this cancer can recur as a widespread, invasive cancer; therefore, doctors want to be sure that the treatments recommended for ductal carcinoma in situ minimize the likelihood of this type of cancer recurrence. For this reason, doctors held a 1999 Consensus Conference on the Treatment of DCIS to discuss the issues and determine the best approach to treating this cancer.
Breast cancer is a type of cancer in which cancerous cells are found in the tissues of the breast. The breast is made up of different sections, called lobes, and tubes that connect these sections, called ducts. The term
in situ refers to very early breast cancer, confined to its original location of growth.
Ductal carcinoma in situ (DCIS) is a very early breast cancer that occurs in the ducts of the breast. Although this type of cancer is highly curable, if left untreated, it will likely progress to widespread, invasive cancer. 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%, with recurrences being rare. 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). Breast-conserving surgery is usually followed by radiation therapy. Clinical trials are also underway to study the use of lumpectomy, followed by radiation therapy and hormone therapy. When DCIS does recur after treatment, it can usually be detected early with a mammogram and treated successfully; however, on a rare occasion a recurrence may manifest as a widespread, invasive cancer. Therefore, researchers want to ensure that the most effective surgery is performed for each woman with DCIS, that radiation therapy and hormone therapy are used when they are likely to be beneficial, and that the risk of cancer recurrence is minimal.
As part of the Consensus Conference on the Treatment of DCIS, doctors convened to discuss possible guidelines for the most successful treatment of DCIS. The doctors agreed that the overall goal of treatment of women with DCIS is to provide breast-conserving surgery when possible, with optimal cosmetic effect and minimal risk for recurrence.
Mastectomy. With regard to the type of surgery that should be performed, the doctors agreed that mastectomy is still the optimal option for a small percent of women with DCIS, including those with large areas of DCIS, multiple areas of DCIS, or an inability to undergo radiation therapy.
Lumpectomy. Most women with DCIS are candidates for a breast-conserving procedure, should they choose this option. The doctors noted that, following lumpectomy, the risk for cancer recurrence appears to be related to the size of the DCIS tumor and the amount of space, or margin, between the cancerous tissue that is removed and the normal tissue in the breast. The consensus was that lumpectomy is advised for women with small DCIS tumors (2 to 3 cm) for which the surgical margin is 10 mm or more between the cancer cells that are removed and the normal tissue.
Treatment after Surgery. With regard to treatments given after the surgery, the doctors pointed out that radiation therapy used after a lumpectomy decreases the recurrence of cancer. However, because the detection and treatment of recurrences is so effective, it is not clear whether the use of radiation therapy increases survival of women with DCIS. Still, these doctors appeared to prefer the use of lumpectomy followed by radiation therapy regimen at this time. With regard to hormone therapy, 1 large study showed lumpectomy plus radiation therapy plus hormone therapy (the agent called tamoxifen) to be more effective in preventing recurrences than only lumpectomy plus radiation therapy only. However, these doctors pointed out that tamoxifen was not shown to improve survival, and they therefore consider this agent to be of unproven benefit at this time.
Treatment of Recurrence. If DCIS recurs as an invasive cancer (occurs beyond the site of the original cancer growth), the prognosis should still be excellent because of early detection and available treatments. Rarely, the cancer may metastasize, or spread to other parts of the body. If the recurrence is another DCIS, treatment is usually a mastectomy or radiation therapy. Persons who received radiation therapy previously, should undergo a mastectomy. The benefit of a second lumpectomy is unclear, although some women have had this procedure repeatedly without the development of invasive cancer.
Conclusions. From the review at this consensus conference, it appears that the best approach to treating DCIS is to provide each woman with individualized care, with the choice of surgery and followup therapies being based on the size of the DCIS, the surgical margins, as well as the way that the cancer cells look under the microscope. Women who have DCIS can find more information on the disease and its treatment through the National Cancer Institute (cancer.gov) and the Cancer Consultants site (www.411cancer.com). Finally, persons who have DCIS or a recurrence of invasive breast cancer may wish to talk with their doctor about the risks and benefits of participating in a clinical trial in which other new treatments are being studied. Sources of information on ongoing clinical trials that can be discussed with a doctor include a comprehensive, easy-to-use service provided by the National Cancer Institute (cancer.gov) and the Clinical Trials section and service offered by Cancer Consultants.com (www.411cancer.com). (Cancer, Vol 88, No 4, pp 946-954, 2000)
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