Abstract P5-15-02: Beyond the learning curve: Surgical judgment in the approach to breast conserving surgery
Authors: Schnabel F , Billig J , Schwartz S , Chun J ,   Breast Surgery Service at the NYU Langone Medical Center
Published: August 2014

Background: Inadequate lumpectomy margins are associated with an increased risk of ipsilateral breast tumor recurrence in patients undergoing breast conserving surgery for malignant disease. Second surgical procedures are often required to achieve acceptable margins. The purpose of this study was to examine the practice of breast conserving surgery by experienced practitioners, focusing on the approach to margins at the time of primary lumpectomy procedure.

Methods: The NYU Langone Medical Center Breast Cancer Database was queried for patients who underwent breast conserving surgery from 1/2010-1/2013 by experienced breast surgeons. Variables of interest, segregated by surgeon, included: characteristics of additional margins taken at primary lumpectomy surgery, re-excision rates, and rates of conversion to mastectomy. Statistical analyses were performed using Pearson's Chi-Square Test, Spearman's correlation, and descriptive analyses.

Results: During the study period, 988 patients opted for breast conserving surgery for invasive and intraductal breast cancer, including 260 patients who underwent at least 1 re-excision procedure. We excluded 31 patients who had initial surgery outside of NYU, yielding a study cohort of 229 patients. Stage 0 disease was associated with an increased frequency of re-excision procedures (p&lt;0.0001). Re-excision rates differed widely among surgeons (10-36%). The average number of additional margins excised did not correlate with surgeons’ re-excision rates (p = 0.18). Additional margins taken at primary lumpectomy surgery included both false positives and true positives (Table 1). Of note, the number of false positive margin excisions was double the number of true positives. Patients who went on to mastectomy after unsuccessful primary lumpectomy surgery (45 of a total of 59 who converted to mastectomy) frequently did so based on their preference (19/45 = 42%). However, patients who converted to mastectomy after multiple excisions generally did so out of concern for extent of disease.

Conclusions: In our study, patients with pure intraductal carcinoma represented a particular challenge as surgeons’ margin assessment was less accurate than in cases of invasive cancer. Re-excision rates varied by surgeon, and did not correlate with the average number of additional margins taken at the primary lumpectomy procedure. The rate of false positive margins excised exceeded the true positive rate, reflecting the limitations of surgeons’ ability to assess margins intraoperatively. We documented a significant number of patients who opted for conversion to mastectomy after a single unsuccessful lumpectomy procedure, underscoring the need for better methods of intraoperative margin assessment to support the practice of breast conserving surgery.

Table 1: Re-excision rates and approach to margins at primary lumpectomy surgerySurgeonPatients undergoing Re-excision - N (%)Avg Additional Margins Taken (per patient) in Primary LumpectomyFalse Positives - N (%)True Positives - N (%)A67 (23%)139 (10%)26 (6%)B53 (10%)4147 (45%)60 (18%)C14 (19%)217 (20%)6 (7%)D11 (31%)01 (1%)3 (5%)E8 (36%)15 (10%)3 (6%)F27 (11%)118 (11%)10 (6%)G20 (15%)335 (29%)26 (22%)H29 (32%)237 (21%)24 (14%)Total229 (16%)2299 (22%)158 (11%)

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P5-15-02.