Q and A on Margin Width &
Ductal Carcinoma In Situ of the Breast
Q: What is ductal carcinoma in situ (DCIS)?
A: The term "breast cancer" comprises a wide variety of lesions with a wide range of malignant potential. Ductal carcinoma in situ (DCIS) is the noninvasive form of breast cancer. Because no invasion is present, the likelihood of spread is minimal.
Before mammography was commonplace, DCIS was considered to be less predominant. Many patients with DCIS had clinical symptoms, such as a breast lump or bloody nipple discharge.
Today, with more prevalent mammography, DCIS is relatively common. In fact, DCIS represents at least 18 percent of all newly diagnosed breast cancer cases in the United States. Most DCIS lesions currently detected are non palpable (cannot be felt with the fingertips) and are found by mammography.
Q. What's new in DCIS treatment?
A. A study published in the May 13, New England Journal of Medicine, entitled "The Influence of Margin Width on Local Control in Patients with Ductal Carcinoma In Situ (DCIS) of the Breast," has shown that a completely excised DCIS (as determined by margin width) does not require postoperative radiation therapy. The study is authored by Melvin J. Silverstein, M.D., and colleagues at the USC/Norris Comprehensive Cancer Center at the Keck School of Medicine of USC, along with colleagues from the Van Nuys Breast Center, and St. Mary's Hospital, San Francisco.
Q. What is the current standard treatment for DCIS?
A. The treatment for most patients has been mastectomy. Today, some patients with DCIS can be treated with breast preserving surgery.
The National Surgical Adjuvant Breast & Bowel Project (NSABP) strongly advocates excision (lumpectomy) plus radiation therapy for all patients who elect to preserve their breast.
Based on current data, Dr. Silverstein et al believe that not all DCIS patients electing breast preservation require postoperative radiation therapy. Some patients may benefit a great deal by the addition of postoperative radiation therapy - others possibly not at all. Research has shown that there are ways to select the patients with DCIS whose benefit from radiation therapy is so small that the side effects far outweigh the benefits.
Q. Who needs radiation therapy?
A. When tumors are high-grade (aggressive) and the margins are close or involved, radiation therapy may reduce the risk of local recurrence.
Q. Is chemotherapy part of standard DCIS treatment?
A. There is no role for standard chemotherapy in patients with DCIS. Chemotherapy is a systemic form of treatment impacting the entire body. Since DCIS is noninvasive, cure comes with adequate local treatment. With that said, there may be a role for endocrine therapy in the form of tamoxifen. These studies have yet to be published but studies are underway.
Q. Can DCIS be completely removed using a sufficiently wide excision?
A. DCIS is a segmental disease. That is, it generally involves a single ductal system of the breast. That means that complete excision is theoretically possible. The removed tissue should be completely processed by the pathologist and evaluated sequentially. The margins, the distance between DCIS and the edge of the specimen should be measured. If the margins are greater than 10 mm (about half an inch) in every direction, the odds are that the lesion has been completely removed.
Q. Will surgeons and pathologists require special training in order to maintain a margin width of the recommended 10mm or more?
A. Most surgeons are capable of excising DCIS with widely clear margins. Their effort will be helped if the radiologist places multiple marking wires around the tumor before resection. Since DCIS can generally be neither seen nor felt by the surgeon, guide wires make excision much more accurate.
Pathologists need to sequentially process all excised tissue and evaluate it microscopically.
Q. What should this study prompt women diagnosed with DCIS to do?
A. Women with DCIS should get a second opinion. The most important second opinion should come from a pathologist highly experienced in breast disease. In addition, a surgeon and radiation therapist expert in DCIS are also valuable. Most academic medical centers with a comprehensive breast center should have these resources.
The report should confirm that DCIS is present. It should tell the architectural type(s), the size, the nuclear grade, the presence or absence of comedo-type necrosis, and the width of the nearest margin (the distance from the DCIS to the marked edge of the excised tissue) as a minimum.
Q. What options should women discuss with their surgeons?
A. The surgeon treating the patient should carefully review all treatment options, to include, excision only, excision with radiation therapy, and mastectomy with and without breast reconstruction. Patients with wide margins, 10 mm or more, can be considered for excision alone. Patient with intermediate margins 1 to 9 mm should consider either re-excision or radiation therapy. Patients with lesions so large that they require mastectomy should consider a skin-sparing mastectomy with immediate reconstruction. The best reconstructions occur when living autologous tissue (from the patient) is used. The TRAM flap from the abdomen is the tissue of choice.
Q. Will this study have an impact for treatment of other forms of breast cancer?
A. We don't know at this time. The study only evaluated patients with noninvasive breast cancer (DCIS). Additional studies will have to be done with invasive breast cancer. For now, all patients with invasive breast cancer who elect breast conservation need postoperative radiation therapy.
Q. Where can I turn for more information on DCIS treatment?
A. A good place is the breast cancer literature. Some recent citations are listed below. There is a only one textbook entitled "Ductal Carcinoma In Situ of the Breast." It was edited by Melvin J. Silverstein, MD and published by Williams and Wilkins (now Lippincott Williams and Wilkins) in 1997.
Citations:
- Fisher B, Costantino J, Redmond C, et al. Lumpectomy compared with lumpectomy and radiation therapy for the treatment of intraductal breast cancer. N Engl J Med 1993;328:1581-1586.
- Fisher B, Dignam J, Wolmark N, et al. Lumpectomy and radiation therapy for the treatment of intraductal breast cancer: Findings from National Surgical Adjuvant Breast and Bowel Project B-17. J Clin Oncol 1998;16:441-452.
- Silverstein MJ, Lagios MD, Craig PH, et al. A prognostic index for ductal carcinoma in situ of the breast. Cancer 1996;77:2267-2274.
- Silverstein MJ, Lagios MD, Groshen S, et al.The influence of margin width on local control in patients with ductal carcinoma in situ (DCIS) of the breast. New Engl J Med 1999;340:1455-1461
- Silverstein MJ, Poller DN, Waisman JR, et al. Prognostic classification of breast ductal\ carcinoma in situ. Lancet 1995;345:1154-1157.
- Silverstein MJ, Lagios MD, Martino S, et al. Outcome After Invasive Local Recurrence in Patients with Ductal Carcinoma in Situ of the Breast. J Clin Oncol 1998;16 (4):1367-1373.
- Silverstein MJ. Ductal carcinoma in situ of the breast: A Fortnightly Review. Br. J. Med 1998;317: 734-739.
- Silverstein MJ, Rosser RJ, Gierson ED, et al. Auxillary dissection for intraductal breast carcinoma - Is it indicated? Cancer 1987;59:1819-1824.
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