Wider Surgical Margins Do Not Appear To Reduce Local Recurrence Rates in Triple-Negative Breast Cancer
Wider surgical margins did not reduce the rate of local recurrence in women with triple-negative breast cancer treated with breast-conserving therapy, according to the results of a study published in the Annals of Surgical Oncology. Pilewskie et al reported that their data support the definition of a negative surgical margin as no ink on tumor, even in this high-risk group of patients.
Study Details
More than 500 women with triple-negative breast cancer who underwent lumpectomy and had planned whole-breast radiation therapy between 1999 and 2009 at Memorial Sloan-Kettering Cancer Center were the focus of this study. A total of 71 of these women had surgical margins ≤ 2 mm, and 464 had margins > 2 mm. Excluded from the study were patients with positive surgical margins, those receiving partial-breast radiation therapy, and women who did not undergo whole-breast radiation therapy.
The investigators amassed data on patient, tumor, and treatment characteristics, including age at surgery, tumor size, presence of lymphovascular tumor invasion, estrogen receptor and progesterone receptor status, HER2/neu status, and receipt of adjuvant chemotherapy. The mean age of the study population was 55.4 years, and the median size of the tumor was 1.6 cm (range, 0.1?7.3 cm). Nearly 30% of the patients had node-positive disease, and about 25% had lymphovascular tumor invasion.
More than 80% of the women had received adjuvant chemotherapy. A trend toward increased use of chemotherapy in the group with wider surgical margins was noted (P = .05).
No Difference in Local Recurrence Rates
Surgical margin widths of > 2 mm were not associated with reduced rates of local recurrence. There were 37 local, 18 regional, and 77 distant recurrences or deaths as first events at a median follow-up of 7 years.
In the group of 525 patients who completed radiation therapy, the cumulative incidence of local recurrence at 5 years was 4.7% for those with surgical margins ≤ 2 mm (95% confidence interval [CI] = 0?10.0) and 3.7% for those with surgical margins > 2 mm (95% CI = 1.8?5.5; P = .11). The investigators found no difference in local recurrence rates between the two surgical margin groups (P = .06) after controlling for chemotherapy and tumor size. In addition, no difference was seen in the risk of distant recurrence or death (P = .53).
Clinical Implications
There is a definite association between increased rates of local recurrence of breast tumors and positive margins, but the effect of increasing negative surgical marginal width after breast-conserving therapy on local recurrence has been a topic of debate. The acceptable margin width for women undergoing breast-conserving therapy for invasive disease has been controversial among both surgeons and radiation oncologists.
The highest rates of local recurrence have been seen in those with triple-negative breast cancer, noted the investigators. However, their study findings do not support the idea that wider surgical margins improve local recurrence rates, even in this high-risk triple-negative breast cancer cohort. Furthermore, given the low rates of local recurrence in both of their study groups, if a larger sample size were to yield a statistically significant difference, the investigators think it would likely lack clinical meaning.
The investigators concluded, “Although it may seem counterintuitive that more widely clear margins do not reduce local recurrence, an emerging body of literature supports the idea that biology and the use of effective systemic therapy are the major determinants of local control.”
Monica Morrow, MD, of the Department of Surgery, of Memorial Sloan-Kettering Cancer Center in New York, is the corresponding author of the article in the Annals of Surgical Oncology.
This study was funded in part through a grant from the National Institutes of Health and the National Cancer Institute and was the recipient of the 2013 Conquer Cancer Foundation of the American Society of Clinical Oncology Merit Award.
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