For invasive breast cancer, national consensus guidelines state that negative margin width is considered adequate when the tumor is not present on ink when patients are receiving breast-conserving surgery followed by whole breast radiotherapy (RT).1 These guidelines have definitely resulted in fewer repeat surgeries and mastectomies in the United States.2
However, there is concern regarding the new margin guideline recently endorsed—an optimal margin width of DCIS of 2 mm—by the Society of Surgical Oncology, the American Society of Radiation Oncology, and the American Society of Clinic
Therefore, our group looked at our own recent contemporary experience treating DCIS at The University of Texas MD Anderson Cancer Center, reviewing data involving about 1500 patients from 1996 to 2010. These data were recently presented at the American Society of Clinical Oncology Annual Meeting & Exhibition.4,5 The 10-year rate of local recurrence for patients with negative margins of <2 mm versus >2 mm were not significantly different, both being less than 5%. There was no statistically significant difference in local recurrence between patients with <2 mm and >2 mm negative margins who underwent RT (10-year local recurrence rate, 4.8% vs 3.3%, respectively; hazard ratio, 0.8; 95% CI, 0.2-3.2; P = .72) (Figure 1). Being younger than 40 years was also an independent risk factor for local recurrence in patients receiving RT. For patients with close margins and no RT, recurrence rates are about 5 times the risk and in the 30% range. For those patients, we routinely recommend re-excision. MD Anderson utilizes detailed multidisciplinary practices including extensive preoperative/intraoperative pathologic/histologic image-guided assessment of margins; offering some patients with small, low- to intermediate-grade DCIS the option of no RT; the use/magnitude of radiation boost tailored to margin width; and endocrine therapy for estrogen receptor–positive DCIS. These practices can be labor-intensive and require meticulous multidisciplinary collaboration.
Based on our results, about 8% to 10% of cases would need additional surgery, potentially without benefit, when receiving RT; therefore, each case needs to be evaluated by a multidisciplinary team that takes into account the patient’s age, the extent of margin involvement, and the patient’s values. The main issue is that many multidisciplinary groups now use the 2 mm margin as an absolute indication for repeat surgery, and not all patients with DCIS and margins <2 mm need repeat surgery when receiving RT.
We treat DCIS to prevent invasive breast cancer.6 DCIS in and of itself is not harmful to patients. In effect, DCIS really may belong in a high-risk breast lesion category. Screening mammography, since its introduction in the mid-1980s, has resulted in about a 500-fold increase in detection of DCIS, and perhaps a significant proportion of these patients, particularly with low-grade and intermediate-grade DCIS, will not go on to develop invasive breast cancers during the patient’s lifetime.
To address this clinical scenario, there are at least 3 currently ongoing clinical trials globally that are testing the hypothesis that biopsy alone with active surveillance is not inferior to immediate breast-conserving surgery with or without RT for DCIS.7 In the United States, 1 such trial is COMET,8 run by the Alliance Foundation Trials group. It is a randomized trial in which 1200 patients over age 40 years with hormone-receptor–positive DCIS without a mass lesion will undergo stereotactic core biopsy (Figure 2). In a randomized manner, patients will receive guideline-concordant care consisting of breast-conserving surgery with or without radiation and endocrine therapy, versus choice of endocrine therapy alone and then followed for multiple endpoints with the primary being the development of invasive breast cancer on follow-up. The second trial, LORIS,9 based in the United Kingdom, randomizes patients with low- and intermediate-grade DCIS, and the third trial, LORD,10 based in the Netherlands (now through the European Organisation for the Research and Treatment of Cancer cooperative group), is enrolling patients with low-grade DCIS only.
Many of our patients are fearful of the consequences of potential overdiagnosis and overtreatment, and they will welcome the results of these trials. Currently, they are followed closely with 6-month follow-up mammograms in the United States.
DCIS is a common preinvasive breast disease that is detected through screening mammography and often treated similarly to invasive breast cancer. One of the most controversial aspects in the management of breast diseases, and specifically breast cancer, is the appropriate management of DCIS. This brief review highlights important data regarding what constitutes an acceptable negative margin for patients treated with breast-conserving therapy and who receive RT. Not all patients with negative margins less than or equal to 2 mm require repeat surgery when receiving RT, as the local control is extremely high. Outcomes are not significantly different for patients with margins greater than 2 mm, as the results of our large contemporary series indicate. Finally, several key international trials are now addressing the hypothesis that the outcomes of patients with percutaneous biopsy alone for low-risk DCIS are not inferior to outcomes of surgery with or without RT.
Author affiliation: Henry M. Kuerer, MD, PhD, FACS, is with The University of Texas MD Anderson Cancer Center, Houston, Texas.
Address correspondence to: Henry M. Kuerer, MD, PhD, FACS, PH and Fay Etta Robinson Distinguished Professor in Cancer Research, Division of Surgery, Department of Breast Surgical Oncology, The University of Texas MD Anderson Cancer Center, 1400 Pressler St, Unit 1434, Houston, TX 77030; Tel: (713) 745-5043; E-mail: firstname.lastname@example.org.
Financial disclosures: Henry M. Kuerer, MD, PhD, receives compensation from the NEJM Group, Inc and McGraw-Hill publishing for editorial work.
Presented in part at the 16th Annual International Congress on the Future of Breast Cancer, July 15, 2017.