Close and Positive Lumpectomy Margins are Associated with Similar Rates of Residual Disease with Additional Surgery

Current guidelines state that "no ink on tumor" constitutes adequate surgical margins for lumpectomy specimens. However, there remains uncertainty when tumor is close (<1 mm) to multiple inked margins.

All local excisions for invasive breast cancer during 3 years at one center were reviewed. Tumor characteristics, margin status, patient age, reoperations, and pathology of reexcised specimen were recorded. Chi-square analysis and regression models were used to identify factors associated with residual disease upon reoperation.

In 533 lumpectomies for invasive cancer, 60 (11 %) had at least one positive margin, and 106 (20 %) had one or more close margin. Multiple margins were either close or positive in 67 cases. Reoperation was performed in 125 of 533 cases (23 %) for close or positive margins. Positive margins were significantly more likely to undergo reoperation compared with close margins (p < 0.001). On reoperation, 73 of 125 (58 %) demonstrated residual cancer, including 39 of 68 (57 %) with close margins, and 34 of 57 (60 %) with positive margins (p = 0.52). When multiple margins were close or positive, residual cancer was found on reexcision in 45 of 59 (76 %) cases as opposed to 34 of 79 (43 %) cases with only one involved margin (p < 0.001). When controlling for other factors, positive margins were no more associated with residual disease than close margins (p = 0.32), whereas multiple close or positive margins were associated with significantly higher risk of residual disease (odds ratio 6.1; p = 0.002; 95 % confidence interval 2.6-14.45).

The only significant predictor of residual tumor was multiple close or positive margins. It may be appropriate to recommend reexcision for patients with multiple close margins.