J. Yu1, J. Yu1, L. C. Elmore1, A. E. Cyr1, J. A. Margenthaler1 1Washington University,Surgery,St. Louis, MO, USA
Introduction:
During breast-conserving surgery (BCS), additional cavity shave margins may be excised after removal of the primary specimen at the discretion of the surgeon to reduce rates of positive margins. We sought to evaluate the concordance of directed shave margins with disease on pathology and to assess the accuracy of surgeon judgment.
Methods:
Utilizing a prospectively-maintained institutional database, we reviewed all women undergoing re-excision following breast-conserving surgery for invasive breast cancer or ductal carcinoma in situ (DCIS) from 2010-2013. We then identified all patients who had directed shave margins taken due to clinical or radiographic suspicion during the index procedure. Surgeon judgment was considered concordant when the shave margin that was taken corresponded to a positive or close margin on the primary tumor specimen. Positive margins were defined as invasive disease or DCIS touching the edge of the specimen, and close margins were defined as disease within 2 mm of the edge. Descriptive statistics were used in data analysis.
Results:
Of the 384 women undergoing re-excision, 99 patients had additional shave margins taken during their index procedures. 18 (18.2%) patients had invasive carcinoma alone, 27 (27.3%) had DCIS alone, and 54 (54.5%) had both. Of 191 total shave margins, an average of 1.9±0.9 shave margins were taken per patient, and the mean shave margin volume was 10.43 cm3. Ninety-six (50.3%) shave margins were positive for invasive disease or DCIS. However, only 74 (38.7%) shave margins were taken when the corresponding primary tumor margin was positive or close. There was no difference in concordance when the shave was taken for clinical or radiographic suspicion (38.2% vs. 36.6%, p>0.05). Forty-six (24%) shave margins were positive for disease when the corresponding primary tumor margin was negative. On re-excision histology, 66 (66.7%) patients had no disease, 25 (25.2%) had DCIS, 7 (7.1%) had invasive disease and one had both (1.0%).
Conclusion:
Surgeons are limited in their ability to accurately assess margin status intraoperatively which leads to imprecise use of directed shave margins. Implementation of routine shave margins or alternative margin assessment methods may be more likely to reduce the rates of positive margins following BCS, and further research is necessary to define the best standard of practice.