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

BACKGROUND: 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.

METHODS: 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.

RESULTS: 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).

CONCLUSIONS: 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.