Intraoperative Shave Technique Proves Effective in Breast-Conserving Surgery

Anees B. Chagpar, MD, MSc, MPH, MA, MBA
Published: Friday, Mar 08, 2019

Anees B. Chagpar, MD, MSc, MPH, MA, MBA

Anees B. Chagpar, MD, MSc, MPH, MA, MBA

It is well-known that breast-conserving surgery yields the same survival as mastectomy for patients with breast cancer, and it has become the mainstay of surgical therapy for the majority of patients with early-stage disease. Critical to the success of breast-conserving surgery, however, is the achievement of negative margins; a meta-analysis has demonstrated that positive margins have been associated with a 2-fold increase in local recurrence rates.1

Hence, positive margins often result in reexcision. Neither surgeons nor patients want to return to the operating room for another procedure, yet positive margins are found in 20% to 40% of breast cancer cases,2,3 prompting reexcision— an event touted as the “other breast cancer epidemic.”4

Debate is ongoing about what constitutes a positive margin, but recent consensus statements have described a positive margin as tumor at ink for invasive carcinoma,5 or within 2 mm for ductal carcinoma in situ (DCIS).6 For DCIS that is concomitant with invasive disease, without an extensive intraductal component, margins are considered negative if DCIS is not at ink (even if within 2 mm).5 This revision in the definition of a positive margin has resulted in a decline of reexcision rates7; however, the long-term impact of this revision remains to be well elucidated.

Indeed, margin status does not (in absolute terms) predict residual disease.8 Roughly 50% of patients with positive margins will have no further disease and 12% to 14% of patients with negative margins will have cancer left in situ adjacent to the cavity resected. Given that margin evaluation is not an exact science, there remains debate, therefore, on whether all positive margins require reexcision, especially for focal disease,9 anterior margins,10 etc. Data are mixed on the oncologic safety of avoiding reexcision in such patients, so the maxim remains to recommend reexcision for all positive margins.

Several Strategies Fail to Show Benefit

A number of techniques have been evaluated for their value in reducing positive margin rates. To begin, some have felt that the use of preoperative MRI may better define extent of disease and may therefore reduce the positive margin rate by better guiding surgical resection. Sadly, the 2 randomized controlled trials that have evaluated this have not validated this hypothesis: The COMICE trial11 found no difference in positive margin rates between patients who had preoperative MRI and those who did not, and the MONET trial12 paradoxically demonstrated an increase in positive margins associated with the use of preoperative MRI. Some have argued that the value of preoperative MRI may be more evident in patients presenting with DCIS, which tends to be less cohesive and more likely to result in positive margins. However, a recent metaanalysis found that MRI did not significantly affect margin status nor reexcision rates in these patients.13

Others have evaluated various methods of localization of nonpalpable tumors. Although a Cochrane analysis found that no significant differences exist among wire localization, radio-occult lesion localization, and radioactive seed localization in terms of margin positivity and reexcision rates,14 use of intraoperative ultrasound seems to result in a lower positive margin rate. A meta-analysis of 7 prospective studies found that the odds of achievement of negative margins were significantly higher with the use of intraoperative ultrasound (risk ratio, 1.37; 95% CI, 1.18-1.59).15

Still others have argued that intraoperative evaluation of margins may be helpful in reducing positive margin rates. Some utilize intraoperative touch imprint cytology or frozen section, both of which require pathology expertise and may add to operative time. Many surgeons will resect margins where intraoperative imaging suggests a close margin. However, studies that have evaluated this in a robust fashion have not found this to reduce positive margin rates.16,17

Findings Support Shave Approach

Resection of circumferential cavity shave margins, however, seems to consistently reduce positive margin and reexcision rates in both retrospective and prospective studies (Table). Three randomized controlled trials to date have all demonstrated that resection of cavity shave margins reduces positive margin and reexcision rates by at least 50%.17,18

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